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Published on Leave a comment on Overdiagnosis of Thyroid Cancer?

The issue of overdiagnosis and overtreatment rears its head again - this time in a study looking at thyroid cancer detection and death rates. The death rate from thyroid cancer has stayed the same since 1935, as has the number of thyroid cancers presenting with symptoms of thyroid cancer. But...the number of new cases of silent thyroid cancer -- the kind where patients have no symptoms -- almost quadrupled in recent years, and these are the tiny cancers that probably won't cause a problem in the person's lifetime. The researchers then discuss how NOT to find these tiny silent thyroid cancers, so as to avoid overdiagnosis and the harms of overtreatment. From Science Daily:

Increased detection of low-risk tumors driving up thyroid cancer rates, study finds

Low-risk cancers that do not have any symptoms and presumably will not cause problems in the future are responsible for the rapid increase in the number of new cases of thyroid cancer diagnosed over the past decade, according to a Mayo Clinic study published in the journal Thyroid. According to the study authors, nearly one-third of these recent cases were diagnosed when clinicians used high-tech imaging even when no symptoms of thyroid disease were present.

"We are spotting more cancers, but they are cancers that are not likely to cause harm," says the study's lead author, Juan Brito Campana, M.B.B.S., an assistant professor of medicine at Mayo Clinic. "Their treatment, however, is likely to cause harm, as most thyroid cancers are treated by surgically removing all or part of the thyroid gland. This is a risky procedure that can damage a patient's vocal cords or leave them with lifelong calcium deficiencies." Dr. Brito says harm is not limited to physical suffering. "Treatment can cause financial hardship for patients and their families and for society as a whole, as millions of dollars are spent for unnecessary and problematic surgeries," he says....At the same time, the incidence of thyroid cancer is increasing more rapidly than that of any other cancer and is on track to become the third most common cancer in women.

In this study, Dr. Brito and his colleagues drew on data from the Rochester Epidemiology Project. They analyzed the records of 566 men and women who were diagnosed with thyroid cancer in Olmsted County, Minnesota, between 1935 and 2012. Specifically, they examined the number of new cases of thyroid cancer, the deaths due to the disease, and the method of diagnosis.

Researchers found that the number of new cases of thyroid cancer doubled in recent years -- from 7.1 per 100,000 people from 1990 to 1999 to 13.7 per 100,000 people from 2000 to 2012. Over the same period, the number of new patients with thyroid cancer presenting with symptoms of thyroid cancer remained the same. In contrast, the number of new cases of silent thyroid cancer -- the kind where patients have no symptoms -- almost quadrupled. The proportion of patients with thyroid cancer who die of the disease has not changed since 1935.

The study found that the most frequent reasons for identifying silent thyroid cancer were review of thyroid tissue removed for benign conditions (14 percent); incidental discovery during an imaging test (19 percent); and investigations of patients with symptoms or palpable nodules that were clearly not associated with thyroid cancer, but triggered the use of imaging tests of the neck (27 percent)."We are facing an epidemic of diagnosis in thyroid cancer," says Dr. Brito. 

Researchers say one approach to curtail the detection of these lesions would be to limit the use of certain imaging technologies. Another tactic would be to engage patients in deliberating their treatment options. In many cases, active surveillance may be preferred over surgery by patients with small, relatively benign cancers that could take decades to grow to any appreciable size or cause life-threatening problems. Dr. Brito thinks something as simple as not using the word "cancer" to refer to these small and silent thyroid lesions could reduce the number of unnecessary treatments for patients with a more favorable prognosis. Rather than calling these lesions thyroid cancer, he would recommend a less emotionally charged term, such as papillary lesions of indolent course.

Thyroid gland. Credit: Mayo Foundation for Medical Education and Research

Published on Leave a comment on Coffee Appears To Have Lots of Health Benefits

A nice summary article about the benefits and risks of coffee consumption. Summary of effects of drinking coffee: 1) May potentially increase blood pressure, but also may lower the risk for coronary disease, and protect against heart disease. 2) May cut stroke risk by as much as 25%, 3) Linked to  improved glucose metabolism, reduced risk for type 2 diabetes, and promotion of weight loss in overweight patients. 4) May reduce the risk for several cancers. 5) Appears to slow the progression of dementia and Parkinson's disease. 6) A significantly decreased risk of developing depression. 7) Slows progression in alcoholic cirrhosis, hepatitis C, and NAFLD (non-alcoholic fatty liver disease). 8) May be beneficial in dry-eye syndrome, gout, and in preventing MRSA infection. 9) May increase blood pressure, anxiety, insomnia, tremor, withdrawal symptoms, and potential increased risk of glaucoma. From Medscape:

How Healthy Is Coffee? The Latest Evidence

Earlier this year, the Dietary Guidelines Advisory Committee (DGAC) released a report[1] stating that up to five cups of coffee per day, or up to 400 mg of caffeine, is not associated with long-term health risks. Not only that, they highlighted observational evidence that coffee consumption is associated with reduced risk for several diseases, including type 2 diabetes, cardiovascular disease (CVD), and neurodegenerative disorders. The body of data suggesting that moderate coffee—and, in all likelihood, tea—consumption is not only safe but beneficial in a variety of mental and medical conditions is growing fast.

A 2012 study of over 400,000 people, published in the New England Journal of Medicine, reported that coffee consumption is associated with a 10% reduction in all-cause mortality at 13-year follow-up.... It's important to note that much of the evidence on the potential health effects of coffee, caffeine, and other foods and nutrients is associational and doesn't prove causality—observational investigations come with limitations and often rely on error-prone methods such as patient questionnaires. However, the sheer volume of existing observational data linking coffee and/or caffeine with various health benefits—as well as, in many cases, evidence of a dose response—suggests that the most widely consumed stimulant in the world has positive influences on our health. 

Cardiovascular Disease:...However, when caffeine is ingested via coffee, enduring blood pressure elevations are small and cardiovascular risks may be balanced by protective properties. Coffee beans contain antioxidant compounds that reduce oxidation of low-density lipoprotein (LDL) cholesterol, and coffee consumption has been associated with reduced concentrations of inflammatory markers. Moderate coffee intake is associated with a lower risk for coronary heart disease as far out as 10 years, and data suggest that an average of two cups per day protects against heart failure.

Cerebrovascular Disease and Stroke: The vascular benefits of coffee are not lost on the brain. According to a 2011 meta-analysis, consuming between one and six cups per day reportedly cut stroke risk by 17%. A 22%-25% risk reduction was seen in a large sample of Swedish women followed for an average of 10 years.

Diabetes:...Numerous studies have linked regular coffee drinking with improved glucose metabolism, insulin secretion, and a significantly reduced risk for diabetes. Most recently, findings from a long-term study published this year suggest that coffee drinkers are roughly half as likely to develop type 2 diabetes as are nonconsumers, even after accounting for smoking, high blood pressure, and family history of diabetes.

Cancer: ...Evidence suggests that moderate to heavy coffee consumption can reduce the risk for numerous cancers, including endometrial (> 4 cups/day), prostate (6 cups/day), head and neck (4 cups/day), basal cell carcinoma (> 3 cups/day), melanoma,and breast cancer (> 5 cups/day). The benefits are thought to be at least partially due to coffee's antioxidant and antimutagenic properties.

Neurodegeneration: Beyond the short-term mental boost it provides, coffee also appears to benefit longer-term cognitive well-being. A 2012 study reported that patients with mild cognitive impairment and plasma caffeine levels of > 1200 ng/mL—courtesy of approximately three to five cups of coffee per day—avoided progression to dementia over the following 2-4 years. On a related note, a study from last year reported that caffeine consumption appears to enhance memory consolidation....Caffeinated coffee has long been thought to be neuroprotective in Parkinson disease (PD)....—as well as in multiple sclerosis. 

Depression: A 2011 study suggests that a boost in coffee consumption might also benefit our mental health: Women who drank two to three cups of coffee per day had a 15% decreased risk for depression compared with those who drank less than one cup per week. A 20% decreased risk was seen in those who drank four cups or more per day. Newer work also suggests that regular coffee drinking may be protective against depression.

Liver Disease: The liver might help break down coffee, but coffee might protect the liver (in some cases). Evidence suggests that coffee consumption slows disease progression in patients with alcoholic cirrhosis and hepatitis C, and reduces the risk of developing hepatocellular carcinoma. A 2012 study reported that coffee intake is associated with a lower risk for nonalcoholic fatty liver disease (NAFLD), while work published in 2014 found that coffee protects against liver fibrosis in those with already established NAFLD.

And That's Not All…: An assortment of other research suggests that coffee intake might also relieve dry-eye syndrome by increasing tear production, reduce the risk for gout, and potentially fight infection. Coffee and hot tea consumption were found to be protective against one of the medical community's most concerning bugs, methicillin-resistant Staphylococcus aureus (MRSA). While it remains unclear whether the beverages have systemic antimicrobial activity, study participants who reported any consumption of either were approximately half as likely to have MRSA in their nasal passages.

And Finally, the Risks: As is often the case, with benefits come risks, and coffee consumption certainly has negative medical and psychiatric effects to consider. Besides the aforementioned potential increase in blood pressure, coffee can incite or worsen anxiety, insomnia, and tremor and potentially elevate glaucoma risk. Also, given the potential severity of symptoms, caffeine withdrawal syndrome is included as a diagnosis in the DSM-5.

Published on Leave a comment on Nearly 70% of Prostate Cancers Can Just Be Watched?

The issue of overdiagnosis and overtreatment has recently been in the news, especially when discussing breast cancer, prostate cancer, and thyroid cancer. Meaning too much unnecessary treatment with harms, when the best approach would have been to do nothing, as studies have suggested or actually shown. Now here is an article in Medscape suggesting that rather than be quick to operate or treat, the best approach for nearly 70% of prostate cancers may be just "watching".

The U.S. Preventive Task Force, which analyzes the value of screening tests, in May 2012 recommended AGAINST routine prostate-specific antigen (PSA)-based screening for prostate cancer for all age groups. According to them, studies do not show that benefits of routine screening of asymptomatic prostate cancer and the resulting treatment outweigh the harms of treatment (e.g., surgical complications including death from surgery, erectile dysfunction, urinary incontinence, bowel dysfunction, and bladder dysfunction), or that prostate cancer treatment even reduces mortality (deaths).

They point out that: "There is convincing evidence that PSA-based screening programs result in the detection of many cases of asymptomatic prostate cancer. There is also convincing evidence that a substantial percentage of men who have asymptomatic cancer detected by PSA screening have a tumor that either will not progress or will progress so slowly that it would have remained asymptomatic for the man's lifetime. The terms "overdiagnosis" or "pseudo-disease" are used to describe both situations." (NOTE: others have argued against this recommendation)

When reading the full Medscape article, it was pointed out that in the study being discussed, one person who was offered active surveillance but declined and was treated with an immediate radical prostatectomy, still died of metastatic prostate cancer. This was an example of a case where when the disease is truly aggressive, it may have spread "like a bird" throughout the body (in Dr. H. Gilbert Welch's terms in his books Overdiagnosed and Less Medicine, More Health) from the very beginning, and may be unstoppable no matter what is done.

I have also noticed reading other prostate cancer studies that a certain percentage of prostate cancers regress from the point of diagnosis (the PSA test and biopsy). In other words, researchers are finding that cancer can have different paths: regresses, stays the same, grows slowly (and can be treated when symptoms appear), or grows very quickly and is so aggressive and unstoppable that it goes through the body "like a bird". And we don't know which will be the aggressive ones when we first find them, thus the controversies over what to do: screen or not?, and treat or not?  ...continue reading "Nearly 70% of Prostate Cancers Can Just Be Watched?"

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Some recent studies looked at aspirin use and cancer and found that consistent use for a number of years (5 to 10 years) lowers the rate of a number of cancers, including colon cancer. However, the longer one takes daily aspirin - then harms start adding up, with a major one being gastrointestinal bleeding. NSAIDs (non-steroidal anti-inflammatory drugs) are also linked to lower rates of various cancers, but harms with long-term use are cardiovascular risks (stroke and heart attack). The first article discusses that many doctors think this lower cancer rate occurs because aspirin and NSAIDs lower inflammation, and as we know, inflammation is linked to cancer.

From Science News: Aspirin reverses obesity cancer risk

Research has shown that a regular dose of aspirin reduces the long-term risk of cancer in those who are overweight in an international study of people with a family history of the disease....They found that being overweight more than doubles the risk of bowel cancer in people with Lynch Syndrome, an inherited genetic disorder which affects genes responsible for detecting and repairing damage in the DNA. Around half of these people develop cancer, mainly in the bowel and womb. However, over the course of a ten year study they found this risk could be counteracted by taking a regular dose of aspirin.

Lots of people struggle with their weight and this suggests the extra cancer risk can be cancelled by taking an aspirin.This research adds to the growing body of evidence which links an increased inflammatory process to an increased risk of cancer. Obesity increases the inflammatory response. One explanation for our findings is that the aspirin may be suppressing that inflammation which opens up new avenues of research into the cause of cancer."

When they were followed up ten years later, 55 had developed bowel cancers and those who were obese were more than twice as likely to develop this cancer -- in fact 2.75 times as likely. Following up on patients who were taking two aspirins a day revealed that their risk was the same whether they were obese or not....What is surprising is that even in people with a genetic predisposition for cancer, obesity is also a driver of the disease. 

The researchers believe the study shows that aspirin is affecting an underlying mechanism which pre-disposes someone to cancer and further study is needed in this area. Since the benefits are occurring before the very early stages of developing a tumour -- known as the adenoma carcinoma sequence -- the effect must be changing the cells which are predisposed to become cancerous in later years.

...continue reading "Aspirin and Cancer"

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Heavy alcohol consumption has been linked to increased risk of several cancers (colorectum, breast, oral , pharynx, larynx, liver, and esophagus). But what about moderate or minimal drinking? The Mediterranean diet and other studies looking at longevity have long viewed a glass of wine a day as beneficial. However, this large study found that even light to moderate drinking is associated with an increased risk of breast cancer in women, and there is an increased risk of alcohol related cancers only among male smokers. From Science Daily:

Light/moderate drinking linked to increased risk of some cancers in women, male smokers

Even light and moderate drinking (up to one drink a day for women and up to two drinks a day for men) is associated with an increased risk of certain alcohol related cancers in women and male smokers, suggests a large study. Overall, light to moderate drinking was associated with minimally increased risk of total cancer in both men and women.

However, among women, light to moderate drinking (up to one drink per day) was associated with an increased risk of alcohol related cancer, mainly breast cancer. Risk of alcohol related cancers was also higher among light and moderate drinking men (up to two drinks per day), but only in those who had ever smoked. No association was found in men who had never smoked.

They used data from two large US studies that tracked the health of 88,084 women and 47,881 men for up to 30 years. They assessed risk of total cancer as well as known alcohol related cancers including cancer of the the colorectum, female breast, liver, oral cavity, pharynx, larynx and esophagus.

Light to moderate drinking was defined as up to one standard drink or 15 g alcohol per day for women and up to two standard drinks or 30 g alcohol per day for men. One standard drink is roughly equivalent to a small (118 ml) glass of wine or a 355 ml bottle of beer....During the follow-up period, a total of 19,269 and 7,571 cancers were diagnosed in women and men, respectively. The researchers found that overall, light to moderate drinking was associated with a small but non-significant increased risk of total cancer in both men and women, regardless of smoking history.

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  In the past few months there has been a lot of discussion about early screening tests for cancer (when there are no symptoms)  versus diagnostic tests (testing once symptoms appear), especially for prostate cancer and breast cancer. Because unfortunately screening also has harms - it is not without significant risks. So the following 2 articles discussing breast cancer are real eye openers. The first article discusses a large study that found that no matter how early the screening and no matter how tiny the cancer and extensive the treatment (e.g, mastectomy of both breasts), in a certain percentage of women the cancer will reappear in a deadly fashion and eventually kill about 3.3% even though they are treated early. The Medscape article points out that it is thought that 28% of early stage breast cancers will progress or reappear as deadly metastatic cancer (even years later) no matter the treatment.

As Dr. Welch has pointed out in his book Overdiagnosis and Less Medicine, More Health - these aggressive cancers are like "birds" - they fly away throughout the body and are deadly no matter when they are diagnosed. A certain percentage of tiny cancers regress (disappear) on their own, others just sit there doing nothing, others grow very slowly (and can be treated successfully when symptoms appear), and then there are those that are so very aggressive that they go throughout the body from the beginning (the birds). And we don't know which will be the aggressive ones when we first find them. So sad..... Meanwhile try to eat healthy foods, get enough sleep, lose weight if overweight, live a healthy lifestyle (don't smoke or drink to excess), and get plenty of exercise in hopes of cancer prevention. I also like to think that each week eating some turmeric (in foods), broccoli famiy foods, olive oil, and berries may also help. Do go read the full original articles. From NY Times:

Early-Stage Breast Condition May Not Require Cancer Treatment

As many as 60,000 American women each year are told they have a very early stage of breast cancer — Stage 0, as it is commonly known — a possible precursor to what could be a deadly tumor. And almost every one of the women has either a lumpectomy or a mastectomy, and often a double mastectomy, removing a healthy breast as well. Yet it now appears that treatment may make no difference in their outcomes. Patients with this condition had close to the same likelihood of dying of breast cancer as women in the general population, and the few who died did so despite treatment, not for lack of it, researchers reported Thursday in JAMA Oncology. 

Their conclusions were based on the most extensive collection of data ever analyzed on the condition, known as ductal carcinoma in situ, or D.C.I.S.: 100,000 women followed for 20 years. The findings are likely to fan debate about whether tens of thousands of patients are undergoing unnecessary and sometimes disfiguring treatments for premalignant conditions that are unlikely to develop into life-threatening cancers.

Diagnoses of D.C.I.S., involving abnormal cells confined to the milk ducts of the breast, have soared in recent decades. They now account for as much as a quarter of cancer diagnoses made with mammography, as radiologists find smaller and smaller lesions. But the new data on outcomes raises provocative questions: Is D.C.I.S. cancer, a precursor to the disease or just a risk factor for some women? Is there any reason for most patients with the diagnosis to receive brutal therapies? If treatment does not make a difference, should women even be told they have the condition?

A majority of the 100,000 patients in the database the researchers used, from a national cancer registry, had lumpectomies, and nearly all the rest had mastectomies, the new study found. Their chance of dying of breast cancer in the two decades after treatment was 3.3 percent, no matter which procedure they had, about the same as an average woman’s chance of dying of breast cancer, said Dr. Laura J. Esserman, a breast cancer surgeon and researcher at the University of California, San Francisco, who wrote an editorial accompanying the study.

The data showed that some patients were at higher risk: those younger than 40, black women, and those whose abnormal cells had molecular markers found in advanced cancers with poorer prognoses. D.C.I.S. has long been regarded as a precursor to potentially deadly invasive cancers, analogous to colon polyps that can turn into colon cancer, said Dr. Steven A. Narod, the lead author of the paper and a researcher at Women’s College Research Institute in Toronto. The treatment strategy has been to get rid of the tiny specks of abnormal breast cells, just as doctors get rid of colon polyps when they see them in a colonoscopy.

But if that understanding of the condition had played out as expected, women who had an entire breast removed, or even both breasts as a sort of double precaution, should have been protected from invasive breast cancer. Instead, the findings showed, they had the same risk as those who had a lumpectomy. Almost no women went untreated, so it is not clear if as a group, they did worse. But some women who died of breast cancer ended up with the disease throughout their body without ever having it recur in their breast — many, in fact, had no breast because they had had a mastectomy. Those very rare fatal cases of D.C.I.S. followed by fatal breast cancer, Dr. Narod concluded, had most likely already spread at the time of detection. As for the rest, he said, they were never going to spread anyway.

Dr. Esserman said that if deadly breast cancers started out as D.C.I.S., the incidence of invasive breast cancers should have plummeted with rising detection rates. That has not happened, even though in the pre-mammography era, before about 1980, the number of women found to have D.C.I.S. was only in the hundreds. Nearly 240,000 women receive diagnoses of invasive breast cancer each year.

Those facts lead Dr. Narod to a blunt view. After a surgeon has removed the aberrant cells for the biopsy, he said, “I think the best way to treat D.C.I.S. is to do nothing." ... Others drew back from that advice.

From Medscape:  The Mystery of a Common Breast Cancer Statistic

A commonly cited breast cancer statistic — that 30% of all early-stage breast cancers will progress, despite treatment, to deadly metastatic disease — appears to have no strong contemporary evidence to back it up. Nonetheless, the statistic appears widely...."It is estimated that 20% to 30% of all breast cancer cases will become metastatic," said the MBCN in response, repeating a statistic from its own website.

The primary source for this declaration is a 2005 CME review on metastatic disease published in the Oncologist by prominent medical oncologist Joyce O'Shaughnessy, MD, from Baylor University in Houston."Despite advances in the treatment of breast cancer, approximately 30% of women initially diagnosed with earlier stages of breast cancer eventually develop recurrent advanced or metastatic disease," Dr O'Shaughnessy wrote.

According to the National Cancer Institute (NCI), the definition of early-stage breast cancer is that which has not spread beyond the breast or the axillary lymph nodes. The range includes stage I, stage IIA, stage IIB, and stage IIIA disease....According to experts, early breast cancers are known to metastasize at 20 years or beyond.

 

Dr Brawley worked with two ACS epidemiologists to examine the issue. They looked at breast-cancer-specific mortality (as identified on death certificates) in 12 health districts in the United States from 2008 to 2012. They were surprised by the finding: "28% of the women who died of breast cancer during that time period had localized disease at diagnosis," said Dr Brawley. The result was unexpected. "We all thought 30% was too high," said Dr Brawley.

(NOTE: Photo credit: Wikipedia Commons of Edouard Manet- Blond Woman With Bare Breasts.)

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For many years it was thought that yo-yo dieting resulted in higher cancer risk. So the findings of this study are a relief. Researchers looked at weight cycling (yo-yo dieting) and incidence for all cancer and 15 individual cancers among more than 132,000 participants during 17 years of study and found NO association with overall risk of cancer or any individual cancer. So feel free to diet and lose weight for the health benefits. From Science Daily:

Yo-yo dieting not associated with increased cancer risk

The first comprehensive study of its kind finds weight cycling, repeated cycles of intentional weight loss followed by regain, was not associated with overall risk of cancer in men or women. The study by American Cancer Society investigators is the largest to date to investigate weight cycling with cancer risk....Weight cycling was also not associated with any individual cancer investigated. The authors of the study say people trying to lose weight should be encouraged to do so even though they may regain it.

With almost half of American adults reporting they are trying to lose weight, and with most weight loss not maintained, weight cycling is very common. Previous studies in animals and humans had suggested that weight cycling may affect biological processes that could lead to cancer, such as increased T-cell accumulation, enhanced inflammatory responses in adipose tissue, and lowered natural killer cell cytotoxicity. However, many of these findings have not been replicated, and at least two previous studies showed no associations between weight cycling and cancer.

For the latest study, researchers led by Victoria Stevens, PhD, American Cancer Society Strategic Director, Laboratory Services, examined weight cycling and cancer among more than 132,000 men and women enrolled in the Cancer Prevention Study II Nutrition Cohort. Begun in 1992/1993, the Nutrition Cohort gathered detailed dietary information from men and women ages 50 to 74 participating in the Society's larger Cancer Prevention Study II, to explore nutrition's effect on and cancer incidence and mortality. Investigators looked at weight cycling and incidence for all cancer and 15 individual cancers. More than 25,000 participants developed cancer during 17 years of study.

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 The following article supported what I have been reading over the past few years: that medical tests and treatments also have downsides, that it is possible to "know too much", that more harm than benefits can occur from certain tests, procedures, and medicines, and lifestyle changes (eat a less processed more plant-based diet, move more, and don't smoke) can be better than some medicines or certain procedures. The doctor mentioned in this article (Dr. H. Gilbert Welch) recently published a book aimed at the general public which I just read and highly recommend: Less Medicine, More Health. Dr. Welch is an academic physician, a professor at Dartmouth Medical School, and a nationally recognized expert on the effects of medical testing. In 2012 he published the well regarded and more technical and in-depth book on this issue: Overdiagnosed: Making People Sick in the Pursuit of Health. From The Atlantic:

The Downside of Medical Screening

If you had a disease, and you could find out sooner rather than later, why wouldn’t you?Medicine has long focused on early detection of diseases as part of a move toward preventive care. But imperfect tests, false positives, and overdiagnosis mean that sometimes the tests do more harm than good, and in recent years, there have been more recommendations to reduce some kinds of screening, including pap smears, colonoscopies, mammograms, and even annual pelvic exams.

“This is something we all need to understand, the two sides of early detection. It does help people, but it’s almost guaranteed to harm others,” said H. Gilbert Welch, a professor of medicine, public policy, and business administration at Dartmouth College, and author of the book Should I Be Tested for Cancer? (He reveals his answer in the book’s subtitle: “Maybe not.”)

The more you look for disease, the more you find it. And in the case of cancer, it’s hard for doctors to know if what they find is dangerous and needs to be addressed, or if it’s just a small tumor that won’t grow and poses no threat. “We can’t be sure which is which, so we treat everybody,” Welch explained at the Aspen Ideas Festival’s Spotlight Health session. “That means we’re treating people who will never experience problems from their disease.”

But they may experience problems from the treatment.The panel gave the example of prostate cancer, which is very common in men—one in seven American men will be diagnosed with it in their lifetimes. “But it turns out a lot of these cancers are very indolent,” said Jessica Herzstein, a preventive-medicine consultant and member of the U.S. Preventive Services Task Force. Around 30 to 40 percent of men who’ve been treated for prostate cancer likely had “slow-growing tumors that would never have become a threat to the man’s lifespan or health,” according to the Prostate Cancer Foundation.

In other words, “you’re going to die with them, not of them,” Herzstein said, “and the treatments are very very harmful.” Radiation therapy, for example, can cause incontinence and erectile dysfunction, and hormone therapy can cause osteoporosis and depression.

The possibility of a false positive is another downside. Not only could it lead to more invasive follow-up tests or treatments that aren’t needed, but it can also give patients unnecessary anxiety.“If we resolve the test by saying ‘The test was wrong, you’re fine!’, that’s one thing,” Welch said. “But most false alarms aren’t resolved that way. [It’s more like] ‘You don’t have cancer, but you have some abnormality that possibly puts you at a higher risk for cancer, but we’re not going to do anything about it. I think that’s where there can be [mental] harm.”

Ultimately, it comes down to a weighing of the benefits and the harms, and, in the absence of clear evidence, the preferences of the patient. The U.S. Preventive Services Task Force helps identify which tests are beneficial by evaluating and grading them. It gives tests an A if there’s a high certainty of substantial benefit, a B if there’s moderate certainty of substantial benefit, a C if there’s moderate certainty of a small benefit, a D if there’s moderate or high certainty of no benefit, and an I if the evidence is just too insufficient to say.

The task force gave prostate cancer screening a D. HIV screening got an A. For breast cancer screening, an always-controversial topic, the results vary. Breast self-exams got a D. Mammograms got a B, but only for women between 50 and 74 years old. For women in their 40s, the grade is a C, meaning the task force recommends patients and physicians discuss and decide together.

Before getting a screening test, patients should think about what would happen if they get a positive result, and if they’d be ready for it, Welch advised. “If I were to go through this, and have this diagnosis, would I want to have this surgery?” Herzstein asked, posing a hypothetical. Would you want to undergo the biopsy, the chemo, whatever treatments come next? “Maybe you don’t even want to go there if there is no treatment for the disease,” she added. Welch gives an example. “With Alzheimer’s disease that’s a fundamental question: What are you going to do with a positive result?” he asked. 

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A recent report found that when a person is exposed to a little bit (or low doses) of a lot of different commonly encountered chemicals, than the combinations over time may cause changes that increase the risk of cancer (they may initiate cancer). Think about it - we are not exposed to just one chemical at a time (which is how chemicals are tested), but to mixtures or a "chemical soup". It is almost impossible to avoid them. As one of the researchers said: "We urgently need to focus more resources to research the effect of low dose exposure to mixtures of chemicals in the food we eat, air we breathe and water we drink." Testing mixtures of chemicals is currently not required by law.

The effects may be synergistic  - an enhanced effect that is more than the sum of the individual chemicals. And some chemicals may have bigger effects at smaller doses (typical of endocrine or hormone disruptors), than at larger doses - which is not how chemicals are typically viewed (typical view: the more you are exposed to a chemical, the greater the effect). A global task force of 174 scientists looked at 85 common everyday chemicals (at everyday low doses), and 50 were found to support cancer-related mechanisms (processes essential to cancer development). Examples of problematic chemicals that are common in everyday life: triclosan (in many soaps and personal care products), bisphenol A (in many plastics, including can linings), and atrazine (common herbicide or weedkiller). From the LA Times:

Combinations of 'safe' chemicals may increase cancer risk, study suggests

Lots of chemicals are considered safe in low doses. But what happens when you ingest a little bit of a lot of different chemicals over time? In some cases, these combinations may conspire to increase your risk of cancer, according to a new report. “Many [chemicals] have the possibility, when they are combined, to cause the initiation of cancer,” said Hemad Yasaei, a cancer biologist at Brunel University in England, one of the authors of the report. “They could have a synergistic or enhanced effect.”

This is not the way regulators typically think about cancer risk when they evaluate a compound’s safety.Normally, they test an individual chemical on laboratory animals, exposing them to progressively smaller amounts until it no longer causes malignant tumors to grow. Then they take that dose, determine the equivalent for humans, and apply what is called a “margin of safety” by declaring that some small fraction of that low dose is safe for people.

The big assumption driving the margin of safety is that a smaller amount of a chemical is less dangerous than a larger amount. (Think of the familiar axiom, “The dose makes the poison.”) But that’s not true for all chemicals, experts say. Some chemicals, such as those that mimic hormones, may actually be more dangerous at lower doses because the human body is exquisitely attuned to respond to minute amounts of natural hormones such as estrogen and testosterone.

And regulators haven’t required testing of mixtures of chemicals at all...Leroy Lowe, president of Canadian nonprofit Getting to Know Cancer and leader of the report published this week by the journal Carcinogenesis. The new report raises questions about whether this approach is adequate...Humans are exposed to about 80,000 man-made chemicals over their lifetimes, experts say. These chemicals are in the foods we eat, the water we drink and the air we breathe. "We live in a chemical soup,” said toxicologist Linda Birnbaum, director of the National Institute of Environmental Health Sciences, who was not involved in the new study.

The research team — a coalition of 174 researchers from 28 countries — set out to determine whether mixtures of these chemicals, at the very tiny concentrations found in the environment, could plausibly trigger the formation of cancerous tumors. They focused on 85 particular chemicals that were impossible to avoid in modern life, that were likely to disturb biological function and were not thought to pose cancer risks at the very low doses that people tend to ingest them.

The researchers scoured the scientific literature to understand how each of these chemicals could affect 10 important processes that are essential to cancer development. Among them: tumor-promoting inflammation, resistance to cell death and the formation of new blood vessels to feed malignant cells. In addition, they categorized whether each of the chemicals exerted biological effects at very low doses to which humans are ubiquitously exposed. (These doses are so small that they tend to be measured in parts per million or parts per billion.)
Of the 85 chemicals researchers examined, 50 were found to affect cancer-causing processes in the body, even at very low doses.

These 50 everyday chemicals included bisphenol A (used in manufacturing plastics), triclosan (often found in hand sanitizer and anti-bacterial soap) and atrazine (a commonly used herbicide). Since each of these chemicals affects different processes that could lead to cancer — bisphenol A makes cells less sensitive to signals to stop reproducing, for example, while atrazine encourages inflammation — it’s plausible that consuming mixtures of these chemicals is riskier than consuming any one individually.

More details about this report. From Science Daily: Cocktail of common chemicals may trigger cancer

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Again, more research finding that being overweight or obese is associated with an increased risk of breast cancer - specifically higher risk of invasive breast cancer in postmenopausal women. They found that the heavier the woman, the higher the risk, but the risk did not vary with hormone therapy use or race and ethnicity. From Medical Xpress:

Obesity associated with increased breast cancer risk in postmenopausal women

An analysis of extended follow-up data from the Women's Health Initiative clinical trials suggests that postmenopausal women who were overweight and obese had an increased risk of invasive breast cancer compared to women of normal weight, according to an article published online by JAMA Oncology. Obesity is a major public health problem in the United States and obesity has been associated with breast cancer risk in observational studies, systematic reviews and meta-analyses.

The Women's Health Initiative (WHI) protocol measured height and weight, baseline and annual or biennial mammograms, and breast cancer in 67,142 postmenopausal women enrolled from 1993 to 1998 with a median of 13 years of follow-up. There were 3,388 invasive breast cancers. Analysis by the authors found:

  • Women who were overweight (body mass index [BMI] 25 to < 30); obese, grade 1 (BMI 30 to < 35); and obese, grade 2 plus 3 (BMI > 35) had an increased risk of invasive breast cancer compared to women of normal weight (BMI < 25)
  • The risk was greatest for women with a BMI greater than 35; those women had a 58 percent increased risk of invasive breast cancer compared with women of normal weight (BMI < 25)....
  • Obesity was associated with markers of poor prognosis; women with a BMI greater than 35 were more likely to have large tumors, evidence of lymph node involvement and poorly differentiated tumors
  • Women with a baseline BMI of less than 25 who gained more than 5 percent of body weight during the follow-up period had an increased risk of breast cancer....