Research on colorectal cancer and dietary patterns shows that a diet high in processed meats is associated with worsened disease-free survival. The research was carried out by an interdisciplinary research team at Memorial University and the University of Toronto.

Dr. Peter Wang, professor of epidemiology in the Faculty of Medicine, is the principal investigator of this study with graduate students Yun Zhu and Hao Wu, master’s students and recipients of fellowships from the Newfoundland and Labrador Centre for Applied Health Research.

The paper, titled Dietary Patterns and Colorectal Cancer and Survival, was published recently in BMJ Open.

“Dietary patterns are associated with colorectal cancer, but little is known about their roles on survival after a diagnosis of colorectal cancer,” explained Dr. Wang.

The study showed that disease-free survival among colorectal cancer patients was significantly worsened among patients with a high processed meat dietary pattern in terms of higher risk of tumour recurrence, metastasis and death.

Colorectal cancer is the second leading cause of cancer death in Canada and the highest incidence of colorectal cancer and mortality rates are in Newfoundland and Labrador. Dr. Wang noted that the diet in Newfoundland and Labrador consists of a large proportion of processed meat, red meat and insufficient vegetables.

The 529 patients in this study were enrolled through the Newfoundland Familial Colorectal Cancer Registry and diet was assessed using a food frequency questionnaire which included 170 foods, beverages and supplements, plus foods such as salted/pickled meat and smoked/pickled fish.

Three distinct dietary patterns – processed meat, prudent vegetable and high sugar – were identified.

“We found that a high intake of processed meat, red meat, fish and processed fish is associated with decreased disease-free survival for patients who had tumours located in the colon and not the rectum,” said Dr. Wang.

The mechanisms explaining the impact of red and processed meat on colorectal cancer mortality are still unclear, said Dr. Wang.

“However strong carcinogens such as N-nitroso compounds and probably carcinogenic mutagens like heterocyclic amines and polycyclic aromatic hydrocarbons, which have been suggested as significant contributors for the development of colorectal cancer, are found in smoked, fried, or high-temperature cooked meat. Our findings between dietary patterns and colorectal cancer survival may also be explained by the impact of dietary patterns on gut microflora on health outcomes.”

This study showed that the influence of processed meat pattern on survival was evident among women rather than men. Dr. Wang noted that the BRAF gene mutation in women is found to be significantly associated with poor colorectal cancer survival, but further research is needed in this area.