19 May 2017 --- An observational study of 826 patients with stage III colon cancer showed that those who consumed two ounces or more of nuts per week had a 42% lower chance of cancer recurrence and 57% lower chance of death than those who did not eat nuts. However, the benefit of nut consumption was limited to tree nuts, including almonds, walnuts, hazelnuts, cashews, and pecans, a secondary analysis revealed.

“Basic healthy eating can often be overlooked during cancer treatment. This study shows that something as simple as eating tree nuts may make a difference in a patient’s long-term survival,” says ASCO President Daniel F. Hayes, MD, FACP, FASCO. “Nut consumption and a healthy diet are generally factors that clinicians and patients should perhaps pay attention to as they design the approach to treatment for colorectal cancer.”

“Numerous studies in the fields of heart disease and diabetes have shown the benefits of nut consumption, and we felt that it was important to determine if these benefits could also apply to colorectal cancer patients,” said lead study author Temidayo Fadelu, MD, a clinical fellow in medicine at Dana Farber Cancer Institute. “Patients with advanced disease who benefit from chemotherapy frequently ask what else they can do to reduce their chances of recurrence or death, and our study is an important contribution to the idea that modifying diet and physical activity can be beneficial.”

There was no associated reduction in cancer recurrence and death among patients who consumed peanuts or peanut butter. According to the authors, the reason may be that, being legumes, peanuts have a different metabolic composition than tree nuts. Peanuts are by far the most widely consumed nut in the US.

Patients with stage III colon cancer have up to a 70% chance of surviving three years after treatment, which typically includes surgery and/or chemotherapy. While numerous prior studies have looked at diet as a potential cancer prevention tool, this is one of the first in colon cancer to look at the role of nut consumption and its influence on recurrence and mortality, according to the authors.

Researchers were particularly interested in nut consumption because it has been linked to lower incidence of obesity, type 2 diabetes and reduction in insulin resistance. These health conditions represent a state of excess energy and are each associated with a higher risk of recurrence and death from colon cancer.

The authors analyzed the associations between overall nut consumption, and just tree nut consumption, and the risk of cancer recurrence and death. Patients who consumed two or more ounces of all types of nuts per week (19% of all patients in the study) had a 42% lower chance of cancer recurrence and 57% lower chance of death than those patients who did not eat nuts after completion of their cancer treatment. The benefit of eating nuts was consistent across known factors that can influence cancer recurrence, including patient age, body mass index, gender and common genomic changes in the tumor.

“It should be emphasized that the authors are not suggesting that eating nuts should be considered a substitute for standard chemotherapy and other treatments for colon cancer, which have dramatically improved survival,” says Dr. Hayes. “Rather, patients with colon cancer should be optimistic, and they should eat a healthy diet, including tree nuts, which may not only keep them healthier, but may also further decrease the chances of the cancer coming back.”

“We need to look at the potential positive impact of nut consumption on survival at other stages of colon cancer, particularly stage IV. Ultimately, we need to understand how nuts confer this protective effect, as well as possibly conduct a randomized, controlled clinical trial where diet recommendations are given at the start of the study to prove that tree nuts can reduce recurrence and death after treatment for colon cancer,” said Dr. Fadelu.

These findings will be presented at the upcoming 2017 ASCO Annual Meeting in Chicago. This study was funded by the National Cancer Institute, of the National Institutes of Health, and Pfizer.