A diet high in whole grains, fruits, and vegetables—along with exercise and maintaining a healthy body weight—can improve the 5-year survival rate for patients with stage III colorectal cancer, according to a new report published by Van Blarigan et al in JAMA Oncology.
The findings emerged from the first study to look at the combined effect of body mass, physical activity, and diet on survival after colorectal cancer diagnosis. Patients whose lifestyle were consistent with the American Cancer Society (ACS) Nutrition and Physical Activity Guidelines for cancer survivors had a 42% lower risk of death during the study than did patients who were not adherent to the guidelines.
The 5-year survival probability for the patients with high concordance to the ACS guidelines was 85%, compared with 76% for those with low concordance—an absolute reduction of 9% reduction in risk of death at 5 years.
The study comprised 992 patients who were enrolled in the CALGB 89803/Alliance Trial, studying adjuvant chemotherapy. They completed a lifestyle survey midway through their chemotherapy treatment and 6 months after the end of treatment.
Each questionnaire asked about the frequency of consuming 131 items over the past 3 months, with responses from never to six or more times per day. Items included fruits, vegetables, whole grains, refined grains, red and processed meats, and alcohol.
The patients also reported how many hours per week over the past 2 months they engaged in nine common leisure time activities, ranging from 0 to 11 or more hours per week. Each activity was assigned a MET (metabolic equivalent task) value, a measure of energy expenditure.
Added to the diet and physical activity scores was the body mass index (BMI). Although the ACS guidelines recommend that patients maintain a BMI of 18.5 to 24.9, previous studies have found that a larger body mass—BMI of 23.0 to 29.9—has been associated with a lower risk of recurrence of death among patients with colorectal cancer. As a result, the researchers used the latter BMI cut points in analyzing the results.
For each patient, and overall score of 0 to 6 was calculated, with higher scores indicating behavior more consistent with the ACS guidelines.
During the follow-up period, a median of 7 years, there were 335 colorectal cancer recurrences and 299 deaths. Adherence to the ACS guidelines—meaning a score of 5 or 6—was associated with a 9% absolute reduction in the risk of death at 5 years compared with patients who scored from 0 to 4. From these data, the investigators hypothesized that 38% of deaths among patients with stage III colon cancer could be prevented if all patients followed the ACS guidelines.
Breaking down the individual guideline data, the researchers found that patients with a BMI of 25.0 to 29.9 had a lower risk of death than individuals with a BMI of 30 or higher. Consuming five or more servings per day of vegetables and fruits, and choosing whole over refined grains, were important dietary factors in reducing the risk of recurrence and death.
One surprising finding was that although the guidelines recommend restricting consumption of red and processed meat, the data showed that low intake of those meats was associated with a higher risk of death.
As for consumption of alcohol, the study revealed that heavy drinkers had a slightly increased risk of death compared to abstainers, although that risk was not statistically significant, and patients using low to moderate amounts of alcohol had a nonstatistically significant decreased risk of death.
Despite the strong link between healthy lifestyle choices and reduced risk of death in stage III colon cancer patients, the researchers cautioned because of study limitations, “we cannot conclude that the associations we observed are independent of patients’ prediagnosis lifestyle, or that changing behaviors after diagnosis will achieve the observed results.”
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.