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Colorectal Cancer, Adenocarcinoma of the Colon, Rectal Cancer, Colon Cancer, and Colon Polyps
Vitamin D and colon cancer:
Preventive Health advisor recommends periodic check of vitamin D level for patients suspected of vitamin D deficiency, insufficiency or suboptimal levels for colon cancer prevention which is assessed by physicians using a blood test for the concentration of the compound 25(OH)D.
Moore et al found as of 2007 that neither children nor adults in the US were obtaining the RDA for vitamin D (39).
Bischoff-Ferrari, HA et al made several strong points favoring a role of optimal levels of vitamin D in prevention of colorectal cancer (23):
Colon cancer incidence increases with further distances from the equator and a lower risk of colon cancer or colon adenomas occurs with higher 25-hydroxyvitamin D levels.
Most vitamin D supplementation trials have resulted in inverse relationship of vitamin D supplements to colorectal cancer, and optimal 25-hydroxyvitamin D levels correlated with reduced colon mucosa proliferation.
Colon cancer cells became less aggressive after exposed to vitamin D3 or 25-hydroxyvitamin D in vitro.
The authors found the optimal level of vitamin D for all the health factors examined to start at 75 nmol/L (30 ng/mL), and the best was between 90 and 100 nmol/L (36-40 ng/mL).
Michaëlsson K et al found that a vitamin D level of 24 to 34 ng/ml (60 to 85 nmol/L) approximately translates to a vitamin D dose of 2000 IU/d and corresponded to the lowest cardiovascular-related, cancer-related, and all-cause mortality (37).
Vieth reported that the ideal level of vitamin D intake for adults should be 50 mg (2000 IU) per day (35).
Bosomworth NJ conducted a review of multiple studies, and determined that 500-1500 IU/d of vitamin D reduced cancer mortality and all-cause mortality (36).
See the section on vitamin D for further information.
Garlic:
Aged garlic extract reduced the size and number of colorectal adenomas at a dose of 2.4 mL daily compared to control group after 12 months (3).
Researchers looked at 127 foods regularly used by 41,387 Iowa women age 55-69 years found that garlic was associated with a statistically significant decrease in colon cancer and proved better than fiber or other vegetables (4).
Curcumin (active compound in turmeric):
In mice, curcumin at a dietary amount of 0.2%-0.5%, reduced benign tumors by 39% and 40%, respectively, so researchers extrapolated an equivalent dose recommendation for humans and a daily dose of 1.6 grams of curcumin, believed by the authors to offer potential benefit (5).
A small study on patients with familial adenomatous polyposis were given curcumin 480 mg and quercetin 20 mg orally 3 times daily, and all 5 patients in the study had a decreased polyp number and size from baseline after a mean of 6 months of treatment with a mean percent decrease in the number and size of polyps from baseline of 60.4% and 50.9%, respectively (6).
Minimal adverse side effects from curcumin and no laboratory abnormalities were noted. (6).
See section on turmeric/curcumin for further information.
Diet and colon cancer:
Risk of colon cancer according to Singh and Fraser (7):
Risk of colon cancer was higher in individuals with a consumption high in meat low in legumes, and with high body mass compared to consumption low in meat, high in legumes and with low body mass.
Eating meat at least 1 time per week had an 85% higher risk of colon cancer than non-meat eaters
Eating red meat at least 1 time per week had a risk 1.9 times higher than those who abstained from eating red meat.
Eating white meat at least 1 time per week had a risk 3.2 times that of those who abstained from eating white meat.
Legume consumption of >2 times/week compared to less than once per week was associated with a 47% lower risk of colon cancer.
Finally, a body mass index >25.6 kg/m2 was associated with a risk 2.63 times that of a body mass index less than 22.5 kg/m2.
A case-control study of 11 cancer sites in Uruguay found that high consumption of red meat was associated with an increased cancer risk of colorectal cancer (OR= 3.83) (8).
Red meat intake of at least 7 times per week resulted in higher incidence of cancers of the stomach, colon, rectum, pancreas, bladder, breast, endometrium, and ovaries (9).
A study of 35,215 Iowa women aged 55-59 years without a history of cancer were followed until 212 of them developed colon cancer and factors found to be associated with increased risk of colon cancer were consumption of sucrose, height, and body mass index, but meat intake did not have an increased risk in this study (10).
After mice were fed Purina, casein or whey protein for 24 weeks, and compared to either the casein or Purina diet mice, whey protein-fed mice had a lower number of new tumors (11).
Slattery, ML et al found the following regarding colon cancer risk (12):
Those that ate 5.5 servings of vegetables per day had 28% lower risk of rectal cancer when compared to people eating less than approximately two servings per day
Those that ate more than 3.5 servings of fruit per day had 27% lower risk of rectal cancer when compared to people eating less than approximately one serving per day.
Those that ate 3 servings of whole grains per day had 31% lower risk of rectal cancer when compared to people eating less than one-half of a serving of whole grains per day
Those that ate more than 34 grams of fiber per day had 46% lower risk of rectal cancer when compared to people eating less than 16 grams of fiber per day
Those that ate more than more than 4.5 servings of refined grains (such as white bread, doughnuts, bakery goods, cookies and cakes) daily had 42% higher risk of rectal cancer when compared to people eating less than 1.5 servings of refined grains per day.
Verhoeven, DT et al found that most case-control studies found an inverse association between brassica vegetable intake (the broccoli family including cabbage, kale, broccoli, Brussels sprouts, and cauliflower) and a lower the risk of many cancers, but especially lung and digestive tract cancers (13).
Comparing those who ate the most legumes (top 33%) against those who ate the least legumes (bottom 33%), high consumption of legumes was associated with a significant decrease in colorectal cancer risk (57% risk reduction) (14).
Green tea and colon cancer:
Men consuming at least 300 grams of green tea per month experienced reductions odds of developing colon cancer, rectal cancer, and pancreatic cancer in men by 18%, 28%, and 37%, respectively and women taking 200 grams of green tea per month had reduced odds of the same cancers by 33%, 43%, and 47% respectively compared to non-tea drinkers (15).
Women age 40-70 who drank 3 or more cups of mostly green tea each week for 6 months were allowed in a study and after following for 11 years, they were noted to have 14% lower risk of colon, stomach and esophageal cancers, and 21% lower risk for 2-3 cups of green tea daily compared to non-tea drinkers (16).
Coffee and colon cancer:
The highest vs. the lowest category of coffee consumption showed a significant reduction in colon and colorectal cancer of 21% and 15% respectively (17).
96,162 subjects (46,023 men and 50,139 women) were evaluated for coffee consumption and it was found that women drinking 3 or more cups of coffee a day had half the risk of developing colon cancer (but not rectal cancer) compared with those who drank no coffee at all, but no benefit in colon cancer risk reduction was found in men (18).
Resveratrol and colon cancer: Animal models of colon cancer found that resveratrol not only reduced the number of lesions before the formation of a tumor but also reduced the risk of developing new tumors and the multiplicity of tumors (19).
Indian gooseberry, scientific name: Phyllanthus emblica, a.k.a. amla and colon cancer: Indian gooseberry extract at 50-100 microg/mL significantly inhibited cell growth of colorectal cancer cells in vitro (20). This is an agent likely safe in amounts used in Indian cooking, but requires further investigation in humans.
Folic acid and colorectal adenomas: Over a 3 year study with healthy adults over age 50 who took folic acid at a dose of 1 mg daily for 3 years, 14.88% of participants taking folic acid developed colorectal adenomas vs. 30.70% in the placebo group and authors believed that those with low levels of folate may be at higher risk of colorectal adenomas (21).
Vitamins A, C, and E and colonic adenoma: Subjects randomized to receive (1) vitamin A (30,000 IU per day), vitamin C (1 gram per day), and vitamin E (70 mg per day); (2) lactulose; or (3) placebo for 18 months were found to have a reduced adenoma recurrence of 5.7% of the vitamin group compared to 14.7% in the lactulose group and 35.9% in the placebo group (22).
Glucosamine, chondroitin, fish oil, methylsulfonylmethane, St John’s wort, and colorectal cancer: Use of glucosamine and chondroitin over the previous 10 years appeared to reduce the risk of colorectal cancer occurring by 27% less for glucosamine, 35% less for chondroitin, 35% for fish oil, 54% less for methylsulfonylmethane, 65% less for St. John’s wort, but garlic pills appeared to have a 35% higher risk colorectal cancer occurrence (24).
Aspirin, nonsteroidal anti-inflammatory drugs, (NSAIDs) and colon cancer:
The Preventive Services Task Force (USPSTF) and most physicians do not recommend aspirin solely for colorectal cancer prevention because higher doses than those used for cardiovascular disease/stroke prevention are required to accomplish this goal. The risk of gastrointestinal bleeding with and aspirin outweigh the benefits of colorectal cancer prevention. (25)
Bardia A et al however determined as part of a cohort study that cancer incidence and cancer mortality was reduced even in patients that used aspirin infrequently compared to those that never used it. In that study, women with the lowest all-cause mortality took aspirin 2-5 times per week. There was no statistically significant impact on cancer incidence or mortality among women who used non-aspirin NSAIDs, compared to those who did not. (28)
The safest approach is that aspirin should not be used specifically for cancer prevention, but if aspirin is used for cardiovascular disease/stroke prevention, there may be a small added benefit of cancer prevention.
