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H. Gilbert Welch has written extensively about the issue of "overdiagnosis" and resulting  "overtreatment" of cancers. Cancer screening can cause the problem of overdiagnosis (finding small tumors that may never cause problems) and lead to overtreatment (treating unnecessarily, which can cause harm).

But now Welch and coauthor Otis Brawley discuss the issue of how too much screening and diagnostic testing of people thought to be "high risk"  for certain cancers results in more being found - thus the risk factors are "self-fulfilling". And it occurs the most in "scrutiny dependent cancers" - which are cancers that the more you look, the more you find, and the more of what you find is harmless. Many are referred to as slow-growing, indolent, subclinical, or even as precancerous. Prostate cancer, thyroid cancer, breast cancer, melanoma, and  lung cancer are  examples of "scrutiny-dependent" cancers.

Looking so hard and then finding cancer gives a false impression of an increased incidence of some cancers. The authors also said that risk factors in determining  who should be screened should not be cancer diagnosis (e.g. in a family member), but death from cancer. From STAT News:

Too much screening has misled us about real cancer risk factors, experts say

The best-known downside of cancer screening, such as PSA tests for prostate cancer and mammograms for breast cancer, is that they often flag cancers that pose no risk, leading to overdiagnosis and unnecessary, even harmful, treatment. But widespread screening for “scrutiny-dependent” cancers — those for which the harder you look the more you find, and the more of what you find is harmlesscauses another problem, two leading cancer experts argue in a paper published on Monday: increasing the apparent incidence of some cancers. That in turn is misleading doctors and the public about what increases people’s risk of developing cancers — or at least the types of cancer that matter.

“Detecting cancers that would never become apparent is screwing up our understanding of risk factors,” said Dr. H. Gilbert Welch of the Dartmouth Institute for Health Policy and Clinical Practice, co-author of the analysis in Annals of Internal Medicine. The problem is especially clear in prostate, breast, and thyroid cancers, all of which are scrutiny dependent.

Men whose relatives developed prostate cancer are more likely to get PSA and other screening tests, either because they request them or because their physicians, noting their family histories, order them. Men with no such family history are less likely to be screened. .... (More than half of such cancers are so slow-growing that they don’t affect health or longevity.) Men who don’t get screened are less likely to have biopsies and so are less likely to be diagnosed with prostate cancer — not because they develop the disease at a lower rate but because they get screened at a lower rate. What you don’t look for, you don’t find.

“If we biopsied men without a family history of prostate cancer at the same rate that we biopsy men with a family history, we’d find more prostate cancer in them as well,” Welch said. “Family history influences how hard we look for prostate cancer and therefore how much we find. The risk factor becomes a self-fulfilling prophecy.”

2016 study of increased prostate cancer screening in men with a family history of the disease concluded that the risk due to family history has been overestimated by nearly half. “The risk factor of family history is spuriously strengthened because men with a family history are exposed to greater scrutiny,” write Welch and Dr. Otis Brawley, chief medical officer of the American Cancer Society, in the Annals report.

Wealthier, better educated women are, however, more connected to the health care system and therefore get more mammograms, breast ultrasounds, and MRIs. The more scrutiny, the more likely that harmless cases of breast cancer are found. (The idea of “harmless” breast cancer sounds like an oxymoron, but an estimated one-half of breast cancers detected by screening would never cause problems even if undetected and untreated.)

Breast tumors found by imaging are much more likely to be harmless than those discovered by women or their physicians finding a breast lump. Income and education are therefore less likely to be a true risk factor for breast cancer and more likely to be a “risk factor” for undergoing screening. If poorer, less educated women were screened for breast cancer at the same rate as wealthier, better educated women, the socioeconomic risk factor would likely vanish.

Thyroid cancers are also scrutiny dependent, which is why when countries launch screening programs the incidence of the disease skyrockets (but death rates don’t, showing that what’s being found is a false epidemic). 

Welch and Brawley call for less focus on risk factors for developing cancers, since those numbers both determine and reflect who gets screened, and more on risk factors for death from cancer.

A new observational study from Taiwan found that having one of eight chronic diseases, such as heart disease or diabetes, or their markers (e.g. high cholesterol levels as a marker for heart disease), also significantly raises the person's odds of developing cancer or dying from cancer. The study estimated that these diseases or markers accounted for about 20% of all new cancers and 39% of all cancer deaths. That's about the risk of 5 lifestyle factors combined (smoking, alcohol consumption, obesity, unhealthy diet, and lack of exercise) contributing to cancer development and death.

The eight chronic diseases and markers were: cardiovascular disease (markers for which include blood pressure, total cholesterol, and heart rate), diabetes, chronic kidney disease (markers for which include proteinuria and glomerular filtration rate), pulmonary disease, and gouty arthritis (for which uric acid is a marker). The higher the chronic disease and marker score, the higher the risk of developing cancer and cancer death (a dose-response). Chronic diseases and markers were associated with a shortened lifespan -  about 13.3 years in men and 15.9 years in women.

But the good news is that regular physical exercise lowers the risk of developing cancer by about 48% and the risk of cancer death by 27%. That's huge!  So physical exercise and activity could be viewed as "cancer prevention" strategies. The researchers pointed out that additional cancer prevention strategies are avoiding smoking (very important), avoiding excessive alcohol consumption, maintaining healthy weight, and a healthy diet. From Science Daily:

Substantial impact of chronic diseases on cancer risk

Several common chronic diseases together account for more than a fifth of new cancer cases and more than a third of cancer deaths, finds a study published by The BMJ today. The findings show that the cancer risks from common chronic diseases, such as heart disease and diabetes, are as important as those from five major lifestyle factors combined.

A team of researchers based in the US and Taiwan therefore set out to investigate the combined effect of eight common chronic diseases or disease markers (for example, high blood pressure as a marker of heart disease) on cancer risk compared with lifestyle factorsThey also explored whether physical activity could reduce the cancer risk associated with chronic diseases and disease markers. The study involved 405,878 men and women in Taiwan with no history of cancer .... underwent a series of medical tests between 1996 and 2007. .... Participants were followed for an average of 8.7 years.

The researchers found that cardiovascular disease markers, diabetes, chronic kidney disease markers, pulmonary disease, and gouty arthritis marker were individually associated with risk of developing cancer or cancer death. Higher chronic disease risk scores based on these diseases or markers were linked with an increased risk of developing cancer and cancer death, with the highest level associated with a more than twofold increase in risk of developing cancer and a fourfold increase in risk of cancer death.

High chronic disease risk scores were also associated with substantial reduction in life span. The highest scores were associated with 13.3 years of life lost in men and 15.9 years of life lost in women. Together, these chronic diseases and markers accounted for more than one fifth of all new cancers and more than one third of all cancer deaths in this study population, which was similar to the contribution of five major lifestyle risk factors combined -- smoking, insufficient physical activity, insufficient fruit and vegetable intake, alcohol consumption, and obesity.

The researchers also found that physical activity was associated with a nearly 40% reduction in the excess risks of cancer and cancer death associated with chronic diseases and markers. [Original study.]

There have been many posts on this blog about diet, fiber, microbes, and the association of diet with various diseases, such as cancer. A recent journal article by M. Song and A. Chan reviewed studies that looked at the link between diet, gut microbes (the gut microbiota or gut microbiome), and colorectal cancer (what we typically call colon cancer).

In summary, research from the last 20 years has found that diet and colorectal cancer (CRC) go hand in hand, and that diet determines the microbes (microbiota) living in the gut - that is, what you feed the microbes determines what microbes will live and thrive in the gut. Also, certain microbes in the gut are linked to inflammation and cancer formation, and others to its prevention. In other words, there is potential to prevent colorectal cancer with certain diets, and to increase the odds of colorectal cancer with other diets.

What are main dietary factors linked to colorectal cancer? Western diet (lots of processed foods, red and processed meat, low in fiber, refined grains), low levels of dietary fiber, low intake of omega-3 fatty acids from seafood (or fish oil), and obesity. The researchers point out that a Western diet is associated with gut dysbiosis (microbial imbalance), loss of gut barrier integrity, and increased levels of inflammation. What should one do? Basically think to yourself: "I need to feed the beneficial microbes in my gut, so I need to eat lots of fruits, vegetables, whole grains, and seafood (omega-3 fatty acids)" - this is what the researchers call a "prudent pattern diet". And try to maintain a normal weight. Some excerpts from Current Colorectal Cancer Reports:

Diet, Gut Microbiota, and Colorectal Cancer Prevention: a Review of Potential Mechanisms and Promising Targets for Future Research

AbstractDiet plays an important role in the development of colorectal cancer. Emerging data have implicated the gut microbiota in colorectal cancer. Diet is a major determinant for the gut microbial structure and function. Therefore, it has been hypothesized that alterations in gut microbes and their metabolites may contribute to the influence of diet on the development of colorectal cancer.We review several major dietary factors that have been linked to gut microbiota and colorectal cancer, including major dietary patterns, fiber, red meat and sulfur, and obesity

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the fourth leading cause of cancer death in the world. Over the past few decades, numerous epidemiologic studies have identified a range of dietary factors that may potentially promote or prevent CRC. Likewise, increasing evidence has implicated the gut microbiota in CRC development. Biological plausibility is supported by habitation of numerous gut microbes in the large intestine and the functional importance of the gut microbiota in maintenance of the gut barrier integrity and immune homeostasis, the disruptions of which are among the most important mechanisms in colorectal carcinogenesis. Given the critical role of diet in the configurations of gut microbial communities and production of bacterial metabolites, it has been proposed that diet may influence CRC risk through modulation of the gut microbial composition and metabolism that in turn shape the immune response during tumor development.

Although gut bacterial abundance may respond rapidly to extreme changes in diet, predominant microbial community membership is primarily determined by long-term diet, and substantial inter-individual variation persists despite short-term dietary change. .... Thus, this review focuses on the dietary factors that have strong mechanistic support, including dietary pattern, fiber, red meat and sulfur, and omega-3 fatty acid. Given the close link between diet and obesity and the predominant role of obesity in CRC as well as the substantial data linking the gut microbiome to obesity, we also include obesity at the end of the review.

DIETARY PATTERNS: Convincing data indicate that a “Western dietary pattern,” characterized by high intake of red or processed meat, sweets, and refined grains, is associated with higher risk of colorectal neoplasia; in contrast, diets that are rich in fruits, vegetables, and whole grains (“prudent pattern diet”) are associated with lower risk of CRC. Western diets are associated with gut dysbiosis (microbial imbalance), loss of gut barrier integrity, increased levels of inflammatory proteins, and dysregulated immune signatures.

A potential role of the gut microbiota in mediating the dietary associations with CRC risk is suggested by the dramatic difference of the gut microbial structures between populations consuming different diets. Rural Africans, whose diet is high in fiber and low in fat, have a strikingly different gut microbial composition than urban Europeans or African Americans consuming a Western diet, which parallels the lower CRC rates in Africa than Western countries. For example, the African gut microbiota is characterized by a predominance of Prevotella genus that are involved in starch, hemicellulose, and xylan degradation, whereas the American microbiota is predominated by Bacteroides genus with a higher abundance of potentially pathogenic proteobacteria, such as Escherichia and Acinetobacter. .... Moreover, a crossover study indicates that switching African Americans to a high-fiber, low-fat diet for 2 weeks increases production of SCFAs, suppresses secondary bile acid synthesis, and reduces colonic mucosal inflammation and proliferation biomarkers of cancer risk.

Fiber: Numerous prospective studies have linked higher fiber intake to lower risk of CRC. The most recent expert report from the World Cancer Research Fund and the American Institute for Cancer Research in 2011 concludes that evidence that consumption of foods containing dietary fiber protects against CRC is convincing. Besides systemic benefits for insulin sensitivity and metabolic regulation, which have been implicated in colorectal carcinogenesis, fiber possesses gut-specific activities, such as diluting fecal content, decreasing transit time, and increasing stool weight, thereby minimizing exposure to intestinal carcinogens.

Moreover, soluble fiber can be fermented by bacteria in the lumen of the colon into SCFAs [short-chain fatty acids], including butyrate, acetate,and propionate. Higher fiber intake has been shown to enrich butyrate-producing bacteria in the gut, such as Clostridium, Anaerostipes, Eubacterium, and Roseburia species, and increase production of SCFAs. SCFAs have been suggested as the key metabolites linking the gut microbes to various health conditions, especially CRC

Red Meat and Sulfur: There is convincing evidence that red and processed meats are associated with increased risk of CRC. Recently, the Int. Agency for Research on Cancer has classified processed meat as a carcinogen to humans. Mechanisms underlying the pro-cancer effects of red or processed meats include heme iron, N-nitroso compounds, or heterocyclic amines, and hydrogen sulfide production. Hydrogen sulfide has been implicated in inflammatory disorders associated with risk of CRC, such as ulcerative colitis, and directly with CRC.

Omega-3 Fatty Acid: Marine omega-3 polyunsaturated fatty acid, including eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid, possesses potent anti-inflammatory activity and may protect against CRC. Fish oil, a rich source of omega-3 fatty acid, is the most popular natural product used by US adults. Substantial data support the beneficial effect of omega-3 fatty acid on CRC prevention and treatment.

Dietary fat composition is a major driver of the gut microbial community structure. Compared to other types of fat, omega-3 fatty acid have been associated with higher intestinal microbiota diversity and omega-3 fatty acid-rich diet ameliorates the gut dysbiosis induced by omega-6 polyunsaturated fatty acid or antibiotics.

Obesity: Since the 1970–1980s, the prevalence of obesity has markedly increased worldwide. The obesity epidemic is believed to be largely driven by global westernization characterized by overconsumption of easily accessible and energy-dense food and a sedentary lifestyle. Obesity is an established risk factor for CRC and several other cancers. Possible mechanisms include increased insulin levels and bioavailability of insulin-like growth factor 1, altered secretion of adipokines and inflammatory cytokines, and changes in sex hormone levels.

There are health benefits to babies from being breastfed, including that breast milk contains hundreds of microbial species which are transmitted to the baby. There are also health benefits to the mother, including a lower risk of breast cancer and ovarian cancer. In addition, a multicenter study in the United States found that breastfeeding lowers the mother's risk of type 2 diabetes over the next 30 years - by up to 47%.

In general: the study found that the longer a woman breastfeeds, the lower her risk of developing type 2 diabetes. Thus one can say that breastfeeding has a "protective" effect for type 2 diabetes. From Medical Xpress:

Thirty-year study shows women who breastfeed for six months or more reduce their diabetes risk

In a long-term national study, breastfeeding for six months or longer cuts the risk of developing type 2 diabetes nearly in half for women throughout their childbearing years, according to new Kaiser Permanente research published Jan. 16 in JAMA Internal Medicine. "We found a very strong association between breastfeeding duration and lower risk of developing diabetes, even after accounting for all possible confounding risk factors," said lead author Erica P. Gunderson, PhD, MS, MPH, senior research scientist with the Kaiser Permanente Division of Research.

Women who breastfed for six months or more across all births had a 47 percent reduction in their risk of developing type 2 diabetes compared to those who did not breastfeed at all. Women who breastfed for six months or less had a 25 percent reduction in diabetes risk.

Dr. Gunderson and colleagues analyzed data during the 30 years of follow up from the Coronary Artery Risk Development in Young Adults (CARDIA) study, a national, multi-center investigation of cardiovascular disease risk factors that originally enrolled about 5,000 adults aged 18 to 30 in 1985 to 1986, including more than 1,000 members of Kaiser Permanente Northern California.The new findings add to a growing body of evidence that breastfeeding has protective effects for both mothers and their offspring, including lowering a mother's risk of breast and ovarian cancer.

The long-term benefits of breastfeeding on lower diabetes risk were similar for black women and white women, and women with and without gestational diabetes. Black women were three times as likely as white women to develop diabetes within the 30-year study, which is consistent with higher risk found by others. Black women enrolled in CARDIA were also less likely to breastfeed than white women.

"The incidence of diabetes decreased in a graded manner as breastfeeding duration increased, regardless of race, gestational diabetes, lifestyle behaviors, body size, and other metabolic risk factors measured before pregnancy, implying the possibility that the underlying mechanism may be biological," Gunderson said. Several plausible biological mechanisms are possible for the protective effects of breastfeeding, including the influence of lactation-associated hormones on the pancreatic cells that control blood insulin levels and thereby impact blood sugar.

This study included 1,238 black and white women who did not have diabetes when they enrolled in CARDIA, or prior to their subsequent pregnancies. Over the next 30 years, each woman had at least one live birth and was routinely screened for diabetes under the CARDIA protocol, which included diagnostic screening criteria for diabetes. Participants also reported lifestyle behaviors (such as diet and physical activity) and the total amount of time they breastfed their children.

 Breastfeeding a baby. Credit: Wikipedia Commons, Anton Nossik.

Prostate cancer is something that men worry about, especially because it is the most common cancer in men, and because it can take several forms. On one hand, a tumor can be "indolent" or so slow growing that it just needs to be monitored, or sometimes it can be very aggressive and even lead to death. That's why the possibility of a dietary pattern (what a person eats) having an effect on the cancer's progression or aggressiveness is very exciting - if true, it would be something people could do to improve their prostate cancer outcome. Or perhaps even prevent it in the first place. Studies up to this point have been mixed, with no clear results.

A recent large study conducted in Spain found that those men with prostate cancer who had a high adherence to a Mediterranean diet had a lower risk of aggressive prostate cancer, as compared to those following a typical Western diet (large amounts of fatty dairy products, refined grains, processed meat, caloric beverages, sweets, fast food, and sauces) or a Prudent diet (low-fat dairy products, whole grains, fruits, vegetables, and juices). A Mediterranean dietary pattern is rich in fruits and vegetables, and also fish, legumes, boiled potatoes, olives and olive oil, vegetable oils, and a low intake of juices.

The researchers also discussed that there are many similarities with breast cancer and prostate cancer, including risk factors. They found in an earlier study in Spain that eating a Western diet is associated with breast cancer risk, the Prudent diet is not associated with breast cancer, and the Mediterranean diet seems to be protective for breast cancer. From Medical Xpress:

A more complete Mediterranean diet may protect against aggressive prostate cancer

In a new study published in The Journal of Urology, researchers determined that men who followed a Mediterranean diet, rich in fish, boiled potatoes, whole fruits, vegetables, legumes, and olive oil, and low consumption of juices had lower risk of aggressive prostate cancer (PC) than those who followed other dietary patterns like Prudent or Western diets. ..."Our results show that a diet oriented towards the prevention of aggressive tumors in the prostate should probably include important elements of the Mediterranean diet such as fish, legumes, and olive oil, and suggest that a high intake of fruits, vegetables, and whole grains might not be enough."

The authors explored the relationship between the risk of having PC and dietary patterns as part of the MCC-Spain study, a Spanish case-control study that involved 733 patients with histologically confirmed PC and 1,229 healthy men with a mean age of 66 years from seven Spanish regions. Anthropometric, epidemiologic, and dietary data were collected.

Adherence to the three dietary patterns of Western, Prudent, and Mediterranean, which characterize the dietary habits of the Spanish population, was evaluated, The Western [dietary] pattern includes consumption of large amounts of fatty dairy products, refined grains, processed meat, caloric beverages, sweets, fast food, and sauces. The Prudent pattern involves consumption of low-fat dairy products, whole grains, fruits, vegetables, and juices. Finally, the Mediterranean pattern consists of high consumption of fish, boiled potatoes, fruits, vegetables, legumes, and olive oil, and low consumption of juices. The diets were graded according to the degree of adherence to each pattern and assigned to four quartiles from lower to higher adherence within each pattern.

Only a high adherence to Mediterranean dietary pattern appeared to be associated with a lower risk of aggressive PC. Prudent and Mediterranean dietary patterns showed different effects in low and high grade tumors. 

PC was assessed using Gleason scores of tumor aggressiveness (<6 or ?6) and clinical stage (cT1b to cT4). A Gleason score of <6 typically indicates a less aggressive tumor with generally good prognosis. Lower clinical stage (cT1-cT2a) indicates a tumor that has not spread. Results indicated that for more aggressive and more extensive tumors (Gleason >6 and stages cT2b to cT4), only high adherence to the Mediterranean diet showed a statistically significant protective effect. All other dietary patterns and tumor characteristics showed little or no correlation and did not achieve statistical significance. [Original study.]

For those who need convincing that lifestyle can contribute to development of cancer or its prevention, new medical research has once again supported the importance of lifestyle choices. A report from Australian researchers (with similar findings as a study in the US) stated: an estimated 38% of cancer deaths and 33% of cancer diagnoses could have been prevented with healthy lifestyle choices.

And what were the lifestyle choices that are linked to cancer?  The researchers list 20 separate things (in 8 broad groups) that are known to cause or are linked to cancer. They are: tobacco smoke (smoking or second-hand smoke), dietary factors (low-intake of fruit, non-starchy vegetables, and dietary fiber; and high intake of red and processed meat), overweight/obesity, alcohol, physical inactivity, solar ultraviolet radiation, certain infections (they list 7 infections, such as human papillomavirus, hepatitis B, hepatitis C), and reproductive factors (lack of breastfeeding, menopausal hormone therapy use, combined oral contraceptive use). Note that they found that the #1 most important lifestyle factor is tobacco smoke - and it accounted for about 23% of all preventable cancer deaths in Australia. From Medscape:

One Third of Cancer Deaths Could Be Prevented by Lifestyle

As we head into the festive season, many are looking forward to the tradition of "Eat, drink, and be merry." But as another research paper shows that more than a third of cancer deaths could be prevented by lifestyle, maybe a qualifier should be added:"celebration in moderation." The latest statistics come from Australia, where researchers note that 44,004 cancer deaths occurred in 2013. But an estimated 38% of these deaths and 33% of cancer diagnoses could have been prevented with healthy lifestyle choices, says a research team led by Louise Wilson, MEpi, at the QIMR Berghofer Medical Research Institute and the University of Queensland, Brisbane.

These cancer diagnoses and deaths were seen in Australians of all ages and are directly attributable to 20 known modifiable risk factors within eight categories that are established causes of cancer, the study authors say. The report is published in the February 2018 issue of the International Journal of Cancer.

Smoking was the leading cause of preventable cancer death in Australia in 2013 and accounted for 23% of all cancer deaths. ...Three other categories of modifiable risk factors — poor diet, overweight/obesity, and infections — accounted for 5% of cancer deaths each. In a fifth category, alcohol-related cancer accounted for 2.4% of deaths. Physical inactivity factors were responsible for 0.8% of cancer deaths, overexposure to ultraviolet radiation for 3.2% of cancer deaths, and, in the eighth category, reproductive or hormonal factors were linked to 0.4% of cancer deaths.

In the diet category, risk factors include low intake of fruit, nonstarchy vegetables, and dietary fiber and high intake of red and processed meat. In the infection category, seven cancer-causing agents, including human papillomavirus (associated with cancer of the vulva, vagina, penis, anus, oral cavity, and oropharynx) and Helicobacter pylori (noncardia stomach cancer), are included. Lack of breastfeeding, use of menopausal hormone therapy, and use of combined oral contraceptive use (breast and cervical cancer) are listed as preventable risk factors in the reproductive category.

These findings are in keeping with other research on the role of modifiable lifestyle-related risk factors in cancer prevention. As previously reported by Medscape Medical News, results from a large cohort study in the United States led researchers to conclude that 20% to 40% of cancer cases and related mortality could be prevented by not smoking, maintaining a healthy weight, and exercising regularly. In another report, results from a national online survey undertaken by the American Society of Clinical Oncology showed that, like their Australian counterparts, most US adults don't know alcohol and obesity are major risk factors for cancer[Original study.]

A dividing lung cancer cell. Lung cancer is associated with smoking. Credit: National Institute of Health (NIH). 

 

 The findings of a large study from Denmark were a disappointment for those hoping that women taking or using low dose hormonal birth control (pills, IUD) would not show an increase in breast cancer (like the old higher dose birth control pills). This study found a small increase in the risk of breast cancer with the use of modern birth control pills and with a progestin-only intrauterine device. They pointed out that the biggest risk was in those using hormonal methods for over 10 years and in their 40s (most of the breast cancer cases occurred in this group of women). The risk goes up the longer one uses hormonal contraception.

Due to smaller numbers of women using a birth control patch, vaginal ring, and implants - they were unable to say one way or another if these also are linked to a higher incidence of breast cancer. But the sense from the researchers is that all hormonal contraception has a slight increase in risk of breast cancer. How big an increase in risk? There is a 20% increased risk overall, but the actual numbers are fairly small - 13 per 100,000 women or approximately 1 extra breast cancer for every 7690 women using hormonal contraception for 1 year. From Medical Xpress:

Small risk of breast cancer seen with hormone contraceptives

Modern birth control pills that are lower in estrogen have fewer side effects than past oral contraceptives. But a large Danish study suggests that, like older pills, they still modestly raise the risk of breast cancer, especially with long-term use. Researchers found a similar breast cancer risk with the progestin-only intrauterine device, and they couldn't rule out a risk for other hormonal contraceptives like the patch and the implant.

But the overall increased risk was small, amounting to one extra case of breast cancer among 7,700 women using such contraceptives per year. Experts who reviewed the research say women should balance the news against known benefits of the pill - including lowering the risk of other cancers.

Researchers analyzed health records of 1.8 million women, ages 15 to 49, in Denmark where a national health care system allows linking up large databases of prescription histories, cancer diagnoses and other information. Results were published Wednesday in the New England Journal of Medicine. Novo Nordisk Foundation funded the research, but played no role in designing the study.

Current and recent use of hormonal contraceptives was associated with a 20 percent increased risk of breast cancer. Risk increased with longer use, from a 9 percent increase in risk with less than a year of contraceptive use to a 38 percent increase after more than 10 years of use. Digging further, the researchers found no differences among types of birth control pills. Because of fewer users, the results for the patch, vaginal ring, implant and progestin shot were less clear, but the analysis didn't rule out an increased breast cancer risk for those methods. [Original study.]

A large study by researchers at the State University of NY, of 65,869 postmenopausal women found that those who have a history  of gum or periodontal disease also have an overall higher risk of cancer. The women with a history of periodontal disease also had an increased risk for several specific cancers: breast, esophageal, gallbladder, lung and melanoma cancers. This cancer and gum disease association occurred in both nonsmokers and smokers.

How is periodontal disease "promoting" cancer? How it occurs is still unclear, but one theory suggests the gum disease bacteria are in the saliva, which is swallowed, and so the bacteria get into the gut, esophagus, or lungs. Or bacteria from diseased gum tissues get into "systemic circulation" and so get to distant sites in the body.  One of the researchers pointed out that "Certain periodontal bacteria have been shown to promote inflammation even in tiny amounts, and these bacteria have been isolated from many organ systems and some cancers including esophageal cancers."

From Medscape: Gum Disease and Increased Link to Many Cancers

Brushing, flossing, and regular dental checkups appear to do much more than maintain a healthy smile. Now, a large prospective cohort study shows that postmenopausal women with a history of periodontal disease, including those who have never smoked, are at significantly increased overall risk for cancer as well as site-specific cancers, including lung, breast, esophageal, gallbladder, and melanoma skin cancers.

The study authors note that these results add to the growing body of evidence from smaller studies and studies in men that link periodontal disease to total cancer risk. The Centers for Disease Control and Prevention (CDC) estimate that 47% of adults 30 years of age and older in the United States have some form of periodontal disease, ranging from mild to severe. At age 65 years and older, however, 70% of adults have moderate to severe periodontal disease, according to the CDC.

The study involved almost 66,000 postmenopausal women in the United States, who were enrolled in the ongoing Women's Health Initiative Observational Study (WHI-OS). During a mean follow-up of 8.32 years, the team identified 7149 cancers and found that periodontal disease history was associated with a 14% increased total cancer risk. When analyses were limited to 34,097 never-smokers, there was also an increased risk for overall cancer.

An association between periodontal disease and site-specific cancers was observed in breast, lung, esophageal, gallbladder, and melanoma skin cancers. There was a borderline association with stomach cancer, the study authors report, and periodontal disease was not associated with cancers of the pancreas; liver; lower digestive tract organs; or lip, oral cavity, and pharynx combined. Similarly, there was no association with genitourinary and lymphoid and hematopoietic malignancies.

For the study, the investigators looked at periodontal disease information in 65,869 women aged 54 to 86 years at 40 US centers. Mean age was 68 years. Most women were non-Hispanic whites with some college education. All participants answered the question "Has a dentist or dental hygienist ever told you that you had periodontal or gum disease? (No/Yes)" between 1999 and 2003 on the annual Year-5 WHI-OS follow-up questionnaire. Cancer outcomes were documented through September 2013 with a maximum 15-year follow-up period.

 Women who reported a history of periodontal disease were also more likely to report a history of smoking, secondhand smoke exposure, alcohol use, hormone therapy (estrogen plus progestin), and a cancer diagnosis, the study authors report. At the same time, no significant differences were observed in body mass index, physical activity levels, or history of diabetes between women with periodontal disease and those without. [Original study.]

A recent study found that significantly increasing  dietary fiber intake after a diagnosis of colorectal cancer was associated with a lower death rate - from both colorectal cancer and overall mortality (from any cause). The 1575 men and women (all healthcare professionals) in the study had received a nonmetastatic colorectal cancer diagnosis (it had not spread beyond the colon), and the follow-up was about 8 years. These results were from food, not supplements.

How much did extra dietary fiber lower the death rate? For each additional 5  grams of fiber added to their daily diet (after diagnosis) was associated with a 18% lower colorectal cancer death rate, and a 14% lower death rate from any cause. In this study, whole grains, especially in cereals, were found to be the most beneficial. Current dietary guidelines recommend a fiber intake of 25 to 38 grams per day, but most Americans eat far lessDietary fiber is found in plant foods, such as beans, whole grains, nuts, seeds,  vegetables, and fruits. Plant fiber feeds the millions of gut microbes, especially beneficial microbes (here, here, and here) - something that was not really discussed in the study.

The researchers pointed out that a high fiber diet (especially from whole grains and cereals) is linked to a lower risk of getting colorectal (colon) cancer in the first place.  Also, that "higher intake of fiber, especially cereal fiber", has been linked to improved insulin sensitivity, reduced inflammation, type 2 diabetes, cardiovascular disease, and total mortality. Other studies have found that  vitamin D supplementation, exercise, and eating fish all increase survival from colorectal cancer. From From Medical Xpress:

Fiber-rich diet boosts survival from colon cancer

A diet rich in fiber may lessen the chances of dying from colon cancer, a new study suggests. Among people treated for non-metastatic colon cancer, every 5 grams of fiber added to their diet reduced their odds of dying by nearly 25 percent, said lead researcher Dr. Andrew Chan. He is an associate professor in the department of medicine at Harvard Medical School.

"What you eat after you've been diagnosed may make a difference," Chan said. "There is a possibility that increasing your intake of fiber may actually lower the rate of dying from colon cancer and maybe even other causes." Chan cautioned, however, that the study does not prove that the additional fiber caused people to live longer, only that the two were associated.

Fiber has been linked to better insulin control and less inflammation, which may account for better survival, he suggested. In addition, a high-fiber diet may protect people from developing colon cancer in the first place. The greatest benefit was attributed to fiber from cereals and whole grains, according to the report. Vegetable fiber was linked to an overall reduction in death, but not specifically in death from colon cancer, and fiber from fruit was not linked to a reduction in death from any cause. 

For the study, Chan and his colleagues collected data on 1,575 men and women who took part in the Nurses' Health Study and Health Professionals Follow-up Study, and who had been treated for colon or rectal cancer that had not spread beyond the colon. Specifically, the study looked at total fiber consumption in the six months to four years after the participants' cancer diagnosis. The researchers also looked at deaths from colon cancer and any other cause. In an eight-year period, 773 participants died, including 174 from colorectal cancer. [Original study.]

Once again the controversial herbicide (weed killer) glyphosate is in the news. Glyphosate is the active ingredient in Roundup (manufactured by Monsanto), and is the most commonly used pesticide in the world. Its use is increasing annually since the introduction of genetically modified crops that are tolerant of glyphosate being sprayed on them (Roundup Ready crops), and since the use of "preharvest" applications of Roundup. Over the years the US government has generally NOT been tracking how much glyphosate residues are in the foods we eat, but whenever a food is studied for glyphosate residues - they are found. (see all posts) Which means people are constantly ingesting low levels of glyphosate residues.

But what does that mean for humans? A  recently published study of 100 adults over the age of 50, residing in Southern California, and followed from 1993 to 2016, looked at detectable glyphosate and its metabolite aminomethylphosphonic acid (AMPA) residues in urine. They found that the number of people with detectable residues in urine, and also the actual levels found in the urine, really, really increased in the 23 years. The percentage of people who tested positive for glyphosate shot up by 500% in that time period - from 12 percent of the samples to 70 percent. WOW!

Are there health effects from constant ingestion in food from low levels of glyphosate? We don't know, because the studies on humans have not been done. There are a number of health concerns, including that it is a carcinogen (it has been classified as a "probable carcinogen" by some agencies), liver and kidney damage, that it acts as an antibiotic and disrupts the gut microbiome, and endocrine disruption. The researchers of this study are especially concerned about possible glyphosate health effects on the liver (liver disease), based on animal studies (animals exposed chronically to very low levels), and want to research this further.

However, the EPA keeps insisting it's safe (and to please ignore the conflicts and deals done with Monsanto in recent years), and actually raised the levels allowed in 2013 (due to corporate lobbying). Also, glyphosate is still not monitored by the Department of Agriculture's pesticide data program or the CDC's (Centers for Disease Control and Prevention) monitoring program of human exposure to environmental chemicals.

What can you do? Try to eat as many organic foods as possible because glyphosate (and Roundup) are not allowed to be used in organic farming. And don't use Roundup on your own property - because you can be exposed to it numerous ways (drinking and eating it in food, inhalation, through the skin).

From Medical Xpress: US study finds rise in human glyphosate levels

Levels of glyphosate, a controversial chemical found in herbicides, markedly increased in the bodies of a sample population over two decades, a study published Tuesday in a US medical journal said. The increase dated from the introduction of genetically-modified glyphosate-tolerant crops in the United States in 1994.

Researchers compared the levels of glyphosate in the urine of 100 people living in California. It covered a 23-year period starting from 1993, the year before the introduction of genetically-modified crops tolerant to Roundup. Glyphosate-containing Roundup, produced by US agro giant Monsanto, is one of the world's most widely-used weedkillers.

"Prior to the introduction of genetically modified foods, very few people had detectable levels of glyphosate," said Paul Mills, of the University of California at San Diego School of Medicine, the study's principal author. Among the study group, detectable amounts increased from an average of 0.20 micrograms per liter in 1993-1996 to an average of 0.45 micrograms in 2014-2016.

In July, California listed glyphosate as carcinogenic, and the World Health Organization International Agency for Research on Cancer called it "probably carcinogenic" in 2015. There are few human studies on the effects of glyphosate, but research on animals demonstrated that chronic exposure can have adverse effects, said Mills. Along with the European Commission's proposal on Tuesday, the European Parliament approved a non-binding resolution calling for the chemical to be banned by 2022.

Excerpts from Consumer Reports: We May Be Consuming More Glyphosate Than Ever Before

A 2016 report in the journal Environmental Health that looked at human and animal studies found a link between glyphosate exposure and a number of health problems, including liver and kidney damage, endocrine disruption, and an elevated risk of non-Hodgkin’s lymphoma. But a vast majority of those studies were done with animals.

In fact, very few human studies have been done on the health effects of glyphosate, and no federal agency monitors how much of the chemical makes it from the environment into our bodies. That lack of information makes it difficult to even begin to assess how much glyphosate is potentially harmful to humans and whether current exposure levels are above or below that mark.