Skip to content

Tag: colorectal cancer

Published on Leave a comment on Forever Chemicals Are Linked To Colorectal Cancer
Intestines Credit: Wikipedia

A number of things can contribute to the development of colorectal cancer (colon cancer), such as highly processed foods, eating a Western diet low in fiber, or the bacteria Fusobacterium nucleatum. These are known to contribute to or result in the gut microbiome being out of whack (gut dysbiosis).

Another factor is perfluorooctanesulfonic acid (PFOS), which are chemicals we all are exposed to in everyday life. A recent study illustrated how long-term exposure to PFOS can also contribute to the development of colorectal cancer because of the effect it has on intestinal cells in the intestines.

PFAS and PFOS (Per- and polyfluoroalkyl substances) are called forever chemicals due to their buildup (bioaccumulation) and persistence in people and the environment. We get exposure to these chemicals various ways - through ingestion (food and water), inhalation (dust), and from absorption through the skin (e.g., personal care products).

They are widely used chemicals, such as in non-stick coatings (e.g., pots and pans) and stain and water repellent products. We get exposure to these chemicals various ways - through ingestion (food and water), inhalation (dust), and from absorption through the skin (e.g., personal care products).

They are in all of us at varying levels, and they have harmful health effects. Effects include cancer, reproductive harm (e.g., poorer semen quality), birth defects, lowered sex and growth hormones in children, thyroid disease, immune effects, and liver and kidney damage. They are endocrine disruptors.

The chemical industry would have you think that the newer PFAS chemicals that replace the older ones are "safer", but guess what? They're not. They're very similar chemically, so it shouldn't be surprising that they don't appear to be safer.

Bottom line: You can't totally avoid PFAS chemicals, but you can lower your exposure to them. If possible, avoid products that are water and stain proof or leak-proof, especially if children will be using the product. Don't use nonstick cookware, stain resistant carpeting and fabrics, clothing treated to be water-proof, and synthetic turf. PFAS and PFOS don't have to be mentioned on labels, so it's buyer beware.

From Medical Xpress: Study links 'forever chemical' PFOS with colorectal cancer

A recent University of Kentucky Markey Cancer Center study sheds light on how the environmental pollutant perfluorooctanesulfonic acid (PFOS) may affect our intestines and possibly increase the risk of developing colorectal cancer. ...continue reading "Forever Chemicals Are Linked To Colorectal Cancer"

Published on Leave a comment on Another Vitamin D Study With Disappointing Results

Recently, another well done study of vitamin D and cancer resulted in disappointing results. Vitamin D supplements showed no benefit in persons with metastatic colorectal cancer (CRC). It did not result in a difference in overall survival outcomes.

In the study, 455 patients with metastatic colorectal cancer were assigned randomly to either high daily vitamin D3 or standard dose vitamin D3, in addition to receiving standard chemotherapy. The high dose vitamin D group received a loading dose of 8000 IU per day for 2 weeks, followed by a maintenance dose of 4000 IU per day until the end of the study. The standard dose vitamin D group received 400 IU per day.

However, there was no difference in "significant progression-free survival benefit". There also was no significant difference in how long people survived in the 2 groups (a median of 25.6 months in the high-dose group, and 27.0 months in the standard dose group).

The study results were disappointing because in laboratory studies vitamin D has anticancer properties. Critics of this study pointed out that vitamin D supplementation may have a role in cancer prevention - but at this point, that is unknown.

From Medscape: High-Dose Vitamin D Disappoints in Metastatic CRC: SOLARIS

The addition of high-dose vitamin D supplementation to standard chemotherapy plus bevacizumab did not result in a significant progression-free survival benefit in patients with metastatic colorectal cancer (CRC) in the SOLARIS study. ...continue reading "Another Vitamin D Study With Disappointing Results"

Published on Leave a comment on Aspirin and Lower Risk of Colorectal Cancer

Studies on aspirin keep coming. For decades, studies found that persons taking aspirin frequently have a lowered risk of developing colorectal (colon) cancer, and that they are less likely to die if they do develop colorectal cancer. A recent study confirmed these aspirin findings and looked at what is occurring.

Aspirin appears to boost or activate the immune system, which helps explain its protective effect in colorectal cancer. Clinical trials are going on now to test whether and how aspirin can be part of colorectal cancer treatment.

From Medscape: How Aspirin May Lower Risk for Colorectal Cancer

A 2020 meta-analysis, for instance, found that 325 mg of daily aspirin — the typical dose in a single tablet — conferred a 35% reduced risk of developing CRC, and a highly cited The Lancet study from 2010 found that a low dose of daily aspirin reduced the incidence of colon cancer by 24% and colon cancer deaths by 35% over 20 years.

The evidence surrounding aspirin and CRC is so intriguing that more than 70,000 people are currently participating in more than 2 dozen clinical studies worldwide, putting aspirin through its paces as an intervention in CRC.

But what, exactly, is aspirin doing?

...continue reading "Aspirin and Lower Risk of Colorectal Cancer"

Published on Leave a comment on A Specific Bacteria and Colorectal Cancer
Credit: Wikipedia

Cancer tumors have a different microbiome (community of microbes) than healthy tissue. Researchers have been finding the bacteria Fusobacterium nucleatum (F. nucleatum) in a number of cancers, with high levels of its presence associated with a poorer outcome for the person (more metastases and death).

A recent study found that one strain or subtype of  F. nucleatum (called Fna C2)  is found in tumors of about 50% of aggressive colon cancers.

Interestingly, F. nucleatum is a normal oral bacteria - one found in the mouth of people, and also associated with periodontal disease. It is rarely found in the gastrointestinal (GI) tract of healthy persons.

It is thought that the bacteria somehow travels from the mouth to the stomach, where it can withstand stomach acid, and then grows there in the gastrointestinal tract. F. nucleatum is cancer promoting - for example, it has a supporting role in tumor progression. It appears to be resistant to cancer treatments.

Researchers are now wondering if certain beneficial or good bacteria ingested by the person or somehow delivered to the tumor site  can battle the F. nucleatum, perhaps as part of cancer therapy. Stay tuned....

From Science Daily: Bacteria subtype linked to growth in up to 50% of human colorectal cancers

Researchers at Fred Hutchinson Cancer Center have found that a specific subtype of a microbe commonly found in the mouth is able to travel to the gut and grow within colorectal cancer tumors. This microbe is also a culprit for driving cancer progression and leads to poorer patient outcomes after cancer treatment. ...continue reading "A Specific Bacteria and Colorectal Cancer"

Published on Leave a comment on Ultra-Processed Foods and Risk of Colorectal Cancer

Once again, bad news about ultra-processed foods. American adults eat so much ultra-processed food that it's now about 57% of their daily calories. It's because these foods are convenient, durable, available everywhere, taste good, and frequently are less expensive than whole foods.

A large study found that eating lots of ultra-processed foods (e.g., prepackaged foods, fast foods) is associated with a higher risk of colon cancer in men. Specifically, a 29% higher risk when compared to men who ate the least ultra-processed foods.

This association was not found in women.

However, when the researchers looked at specific kinds or categories of ultra-processed foods that were eaten, they found differences in colorectal cancer risk. Higher consumption of meat/poultry/seafood based ready-to-eat-products and sugar sweetened beverages (soda!) was associated with a higher colorectal cancer risk in men. Higher consumption of ready-to-eat/heat mixed dishes was associated with colorectal cancer in women.

But interestingly, eating yogurt and dairy based desserts were negatively associated with colorectal cancer risk in women - it's as if they were protective. Perhaps the beneficial microbes in the dairy foods?

Ultra-processed foods are ready-to-eat or ready-to-heat foods made of little or no whole foods. Instead, they are mostly made of substances derived from foods. They typically have many added ingredients such as additives, artificial colors, preservatives, stabilizers, sugars, artificial sweeteners, salt, flavorings, and hydrogenated fats.

Examples are frozen meals, soft drinks, hot dogs, cold cuts, fast food, packaged foods (including cookies and cake), candies, instant soups, and sweet or savory packaged snacks.

Studies also show that ultra-processed foods cause negative or harmful changes in the gut microbiome (microbial community of bacteria, viruses, fungi). Higher consumption is associated with a higher risk of a number of chronic diseases and cancer.

From Science Daily - New study links ultra-processed foods and colorectal cancer in men

For many Americans, the convenience of pre-cooked and instant meals may make it easy to overlook the less-than-ideal nutritional information, but a team led by researchers at Tufts University and Harvard University hope that will change after recently discovering a link between the high consumption of ultra-processed foods and an increased risk of colorectal cancer. ...continue reading "Ultra-Processed Foods and Risk of Colorectal Cancer"

Published on Leave a comment on Antibiotics and Colon Cancer

Antibiotics can be life-saving, but there are also unintended consequences. One of them is that they disrupt and alter the gut microbiome (the microbial community of the millions of microbes living in the intestines). A large study found that use of antibiotics is linked to a higher risk of colon cancer 5 to 10 years later.

The researchers thought this was due to the antibiotics having negative effects on the gut microbiome. Antibiotics reduce numbers of beneficial bacteria in the intestines, while allowing bacteria linked to colorectal cancer to increase.

Researchers at Unea Univ. in Sweden compared 40,545 colon cancer cases to 202,720 controls (no cancer), and found that as antibiotic use increased, colon cancer increased in those persons during the next 10 years. It is unknown what happens after 10 years, because that is when the study ended. Interestingly, in women - increased use of antibiotics was linked to a lower incidence of rectal cancer.

The researchers analyzed the results with respect to different classes  of antibiotics, and found the strongest association with the use of quinolones, sulfonamides, and trimethoprims. These antibiotics have an effect on bacterial diversity - specifically allowing anaerobic Fusobacteria and Bacteroidetes species to live and become more abundant. Other studies also support the view that Fusobacteria (e.g., Fusobacterium nucleatum) and Bacteroidetes species contribute to colorectal cancer development.

What to do? To increase beneficial species in the gut and lower levels of inflammation in the body, studies support eating a diet rich in fruits, vegetables, whole grains, nuts, seeds, legumes, and fish - which also results in a high fiber intake (e.g., Mediterranean diet). Also, to quickly improve the diversity of microbes in the gut (a sign of health!) and to lower inflammation in the body, increase your intake of fermented foods.

Fermented foods include: yogurt, buttermilk, sour cream, cheese, kefir, fermented vegetables, kimchi, natto, miso, sauerkraut, traditional pickles, traditional sourdough bread, apple cider vinegar, and kombucha. To quickly improve the gut microbiome, try to eat six 1/2 cup servings each day for a few months.

From Science Daily: Antibiotics linked to increased risk of colon cancer

There is a clear link between taking antibiotics and an increased risk of developing colon cancer within the next five to ten years. This has been confirmed by researchers at Umeå University, Sweden, after a study of 40,000 cancer cases. The impact of antibiotics on the intestinal microbiome is thought to lie behind the increased risk of cancer.  ...continue reading "Antibiotics and Colon Cancer"

Published on Leave a comment on Time To Stop Drinking Soda?

An interesting study found that high fructose corn syrup promotes the growth of intestinal tumors - in mice. The amount was fairly small - the equivalent of 12 oz of soda (with about 20 g of high fructose corn syrup) per day. The big question now: Is this also true for humans?

A number of studies find an association of soda consumption (which typically has high-fructose corn syrup in it), obesity,  and cancer (e.g. colorectal cancer) in humans, but the question remained whether this was due to obesity (obesity is linked to many types of cancer) or whether the high fructose corn syrup is directly contributing to tumor development or tumor growth. Based on the results of this study, the researchers felt that the high fructose corn syrup "enhances" or "promotes" intestinal tumor growth. Yikes.

From Science Daily: High-fructose corn syrup boosts intestinal tumor growth in mice

Does sugar directly feed cancers, boosting their growth? The answer seems to be 'Yes' at least in mice according to a study led by researchers at Baylor College of Medicine and Weill Cornell Medicine.  ...continue reading "Time To Stop Drinking Soda?"

Published on Leave a comment on Eating Garlic, Onions, and Leeks Linked to Lower Risk of Cancer

Is eating vegetables in the Allium family (garlic, onion, leeks, spring onions, garlic stalks) protective in regards to colon cancer? A recent study from China suggests that eating higher amounts of these vegetables is associated with a lower incidence of colorectal cancer in both men and women.

Interestingly, the researchers only looked at these 5 vegetables, which are commonly eaten in China, but not other Allium vegetables that are commonly eaten elsewhere in the world - such as chives, scallions, and shallots. All Allium vegetables are rich in flavonols and organosulfur compounds, which have properties that inhibit tumors (anti-tumor) in laboratory studies. High intake of Allium vegetables is thought to be protective for a variety of cancers, e.g. prostate cancer.

The researchers mention that other studies examining this issue had mixed results - with some finding a protective effect of Allium vegetables, but not others. The researchers suggested that the high intake of these vegetables in the groups they studied and also cooking methods (which vary among different regions of China, as well as different countries) could explain the differences.

For example, slicing and crushing fresh garlic releases beneficial compounds, but boiling onions leads to an approximately 30% loss of beneficial substances. After reviewing a number of studies that looked at Allium vegetable intake and cancer, it appears that while eating them cooked in any way is good, the most beneficial effects seem to be from raw Allium vegetables.

How much of the Allium vegetables did they eat? The healthy (non-colorectal cancer) group ate about 2 ounces or 1/4 cup of Allium vegetables per day (or 47 pounds annually), versus the colorectal cancer group ate about 1.5 ounces per day (or 15.92 kg or 35 lbs annually).

Other differences between the groups were that the colorectal cancer group had higher intakes of alcohol and red meat, but less milk, other vegetables, and fruit (as compared to the healthy group). But both groups had the same intake of fiber.

Bottom line: eat a diet rich in fruits and vegetables, including Allium vegetables (onions, garlic, leeks, spring onions, chives, scallions, shallots).

From Science Daily: Consuming garlic and onions may lower colorectal cancer risk   ...continue reading "Eating Garlic, Onions, and Leeks Linked to Lower Risk of Cancer"

Published on Leave a comment on Nuts And Colon Cancer

Are there foods that could prevent cancer? Well... studies show that a dietary pattern with lots of fiber, and perhaps along the lines of the Mediterranean diet, may be the most beneficial. In other words, it's not just one or a few "super-foods" that a person should eat, but an overall dietary pattern. But one specific food does appear beneficial for health - nuts, specifically tree nuts.

Researchers at the Yale Cancer Center followed a large group of stage 3 colon cancer patients after they had been treated for about 6.5 years, and looked at how frequently they consumed nuts. (Stage 3 colon cancer means it had spread to lymph nodes, but not to distant sites like the liver and lungs.) They found an association with frequent consumption (2 or more servings per week) of tree nuts (walnuts, hazelnuts, almonds, cashews, pecans, etc.) and a 42% lower incidence of the colon cancer recurring and 57% lower death rate. However, these findings did not apply to peanuts, which are legumes. [NOTE: One ounce or a handful of nuts is considered a serving.]

Why would nuts be beneficial? Generally speaking, nuts lower inflammation and insulin resistance. The lead researcher Dr. Charles Fuchs said that "behaviors that make you less insulin-resistant, including eating nuts, seem to improve outcomes in colon cancer". Parts of this research were discussed last year, but now it has been written up in the Journal of Clinical Oncology. ...continue reading "Nuts And Colon Cancer"

Published on Leave a comment on Diet, Gut Microbes, and Colon Cancer

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

Abstract: Diet 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.