Following lifestyle guidelines about diet, physical activity and maintaining a healthy weight is associated with an improved likelihood of survival when diagnosed with bowel cancer

This is based on the findings of a large study of over 500,000 published in the open access journal BMC Medicine.

Bowel cancer, also called colorectal cancer, is the second most common cancer in men and the third most common cancer in women worldwide, with 55% cases occurring in developed regions such as North America and Western Europe. Survival rates of bowel cancer have wide variations even in people with similar tumors and receiving the same treatment.

It has been suggested that lifestyle factors before and after diagnosis of bowel cancer can influence survival. To investigate this further, a group researchers led by a team from Imperial College London analyzed the data of 520,000 participants from 10 countries in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study.

Lead researcher, Dora Romaguera from Imperial College London and CIBER-OBN, says: "Current advice given to cancer survivors about lifestyle is to follow the same lifestyle recommendations for cancer prevention. Based on results of our own previous work on the EPIC cohort on cancer prevention, we wanted to see if following these recommendations were associated with the survivability of bowel cancer."

At the start of the study, participants completed questionnaires about their medical history, diet and lifestyle. Weight and height measurements were also taken. During the study period of an average of 6.4 years, 3,292 participants were diagnosed with bowel cancer.

The researchers developed a scoring system based on joint guidelines from the World Cancer Research Fund, who funded this study, and the American Institute of Cancer Research with recommendations on cancer prevention. These guidelines have also been recommended to cancer survivors due to the lack of specific guidelines for survivors.

A six-point score was constructed for men based on recommendations in the guidelines about body weight, physical activity, food and drinks that promote weight gain, plant foods (which includes vegetable, fruit, legumes and grains), meat-based food, and alcoholic drinks. Women had seven-point score based on the previous six recommendations and whether or not they had breastfed. Points were allocated based on meeting these recommendations.

It was found that men who had a lifestyle score of 3 or more points were more likely to survive bowel cancer. For women, a score of 4 or above was associated with increased survival; in both cases, the higher the score, the lower the risk of mortality after bowel cancer.

When the individual recommendations were studied, it was found that having a healthy weight and high plant foods consumption had the strongest associations with survival. There was also an association seen with women who breastfed and survival of bowel cancer. This has been seen for breast cancer before but is the first time it has been seen in bowel cancer.

Due to the design of this study, it has not been possible for this study to demonstrate what would happen if these lifestyle habits were acquired after cancer diagnosis. Also, lifestyle was measured only once so it is not possible to know if lifestyle habits changed during follow-up or after cancer diagnosis. Further studies are needed to understand the association of a healthy lifestyle before and after cancer diagnosis and bowel cancer survival.

Dora Romaguera says: "The results of this study demonstrate that a healthy lifestyle in your adult life, in line with recommendations on diet, physical activity and body weight for cancer prevention, do not only prevent developing bowel cancer but, in those who eventually developed it, it improves survival. Adherence to these recommendations was measured at the start of the study, before cancer diagnosis, and represent long-term lifestyle habits."