March is the awareness month of colorectal cancer (CRC). CRC is one of the GI cancers that has shown significant progress in the past 5 to 10 years as far as new clinical insights, therapeutic options and prevention are concerned.
It is a frequent type of cancer. For 2017, an incidence in the US of 135,430 newly diagnosed colon and rectal cancer cases was estimated and 50,260 deaths for men and women combined. Incidence has changed recently. While numbers went up between 1975 and the mid-80s, they declined between then and the early 2000s by 2% followed by 3% between 2004 and 2013. The decline has been attributed to less smoking and improved awareness, screening and removal of precancerous polyps as an effective method to prevent CRC from occurring. (1)
Yet despite less smoking and greater awareness, numbers remain high and recently, a concerning increase in incidence regarding younger people has been reported (2).
Risk factors for CRC are numerous. There are of course risk factors that are out of our control like age, gender, ethnicity, hereditary disease and medical history. However, some life style factors that everybody can pay attention to do play a role as well. Prevention include a healthy diet (fiber, calcium, fruit and vegetables, less alcohol), maintaining a reasonable weight and working out.
Very recently results from the CALGB 89803 (Alliance) study have been presented and published in the high impact Journal of Clinical Oncology by Fadelu et al. Dr. Fadelu asked a very basic but important question: If CRC recurrence and mortality is increased in patients with diabetes type 2, obesity, sedentary lifestyle and high glycemic load diet and nuts as part of a healthy diet lower the risk of type 2 diabetes, metabolic syndrome and insulin resistance, could as a consequence nut intake lower CRC recurrence and survival? The research group conducted a prospective, observational study questioning 826 patients with advanced stage III CRC enrolled in a trial testing adjuvant chemotherapy on dietary intake and food frequency. The results look promising.
Very briefly, in this study, scientists found that stage III colon cancer patients who consumed diets with two or more servings of nuts per week had significantly higher probability of disease free survival and also overall survival. Doing a subgroup analysis, the research group realized that only tree nuts (walnut, almond, hazelnut, cashew, pistachio and Brazil nuts) but not peanuts have this effect. The authors’ hypothesis is that the effect of nuts on hyperinsulinemia and energy balance may in part explain the association between nut intake and improved patient outcome. In fact, nuts are highly nutritious containing unsaturated fatty acids, high-quality protein, fiber, vitamins, minerals, phytochemicals and other bioactive substances impacting metabolism.
Discussing the strengths and weaknesses of their study, the authors are very realistic when they state that their study did not establish causality; however, in the context of other clinical and preclinical data and experience collected by experts, Dr. Fadelu’s important results add to the awareness that diet and lifestyle seem to have a positive effect on outcomes in patients with colon cancer. But again, dose is important! In the study they used two servings of tree nuts per week ……. Let’s keep that in mind …..
1) Colorectal Cancer: Facts & Figures 2017-2019 by the American Cancer Society
3) Fadelu T. et al. (2018) Nut consumption and survival in patients with stage III colon cancer: Results from CALGB 89803. JCO volume 36, number 11, April 10, 2018