Nut consumption reduces risk for colon cancer recurrence
Regular consumption of tree nuts conferred considerable benefit to patients with stage III colon cancer, according to observational study results scheduled for presentation at the ASCO Annual Meeting.
Patients who ate at least 2 ounces of tree nuts per week demonstrated a 42% reduced risk for recurrence and a 57% reduced risk for death compared with those who did not eat tree nuts.
“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,” researcher Temidayo Fadelu, MD, clinical fellow in medicine at Dana-Farber Cancer Institute, said in a press release. “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.”
Seventy percent of patients with stage III colon cancer survive 3 years after treatment, which typically consists of surgery or chemotherapy.
Prior studies have revealed inverse associations between nut consumption and obesity, type 2 diabetes and insulin resistance. These conditions have been linked to higher risk for colon cancer recurrence and death.
“There are a variety of components in nuts, including fatty acids and fiber, and the thought is those impact the way the body releases insulin compared to the consumption of other types of food substances, like simple sugars,” Fadelu said during a press conference. “The exact mechanism is not really clear, but it’s been shown that blood sugar levels and insulin after consumption of nuts usually results in a lower insulin-released system.”
However, no study had assessed whether nut consumption influenced colon cancer recurrence or mortality.
Fadelu and colleagues conducted a prospective observational study that included 826 patients with stage III colon cancer.
All patients completed food frequency questionnaires while enrolled in a randomized CALGB clinical trial that began in 1999. The questionnaire — administered after patients completed adjuvant chemotherapy — assessed patients’ dietary intake, including nut consumption.
Researchers analyzed recurrence and mortality outcomes based on patients’ overall nut consumption and their consumption of tree nuts, such as walnuts, almonds, hazelnuts, pecans and cashews.
DFS served as the primary endpoint.
Nearly one in five (19%) study participants consumed at least 2 ounces of nuts per week. These patients demonstrated significantly reduced risk for recurrence (adjusted HR = 0.58; 95% CI, 0.37-0.92) and death (adjusted HR = 0.43; 95% CI, 0.25-0.74).
Subgroup analysis revealed statistically significant associations only for consumption of tree nuts, with a 46% reduction in risk for recurrence (HR = 0.54; 95% CI, 0.34-0.85) and a 53% reduction in risk for death (HR = 0.47; 95% CI, 0.27-0.82).
In a secondary analysis, Fadelu and colleagues observed no significant association between outcomes and consumption of either peanuts or peanut butter.
“Peanuts are technically legumes, and there are different chemical compositions between peanuts and tree nuts,” Fadelu said. “We don’t really know what the biologic mechanism is for this association, but we hypothesize that it’s perhaps due to the influence of nuts on insulin resistance. There needs to be further studies to evaluate this hypothesis.”
Additional research also is needed to assess the potential effect of nut consumption on survival among patients with other stages of colon cancer, researchers wrote.
“Ultimately, we need to understand how nuts confer this protective effect, as well as possibly conduct a randomized controlled clinical trial [in which] 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,” Fadelu said in the press release.
Basic healthy eating often can be overlooked during cancer treatment, according to Daniel F. Hayes, MD, FACP, FASCO, president of ASCO and clinical director of the breast oncology program at University of Michigan Comprehensive Cancer Center.
“This abstract should not be interpreted as suggesting a patient who has early-stage colon cancer can live a healthy lifestyle and eat tree nuts and forego good standard of care,” Hayes, who was not involved in the study, said during a press conference. “That’s a very dangerous interpretation, and it’s not what we’re trying to get across.”– by Mark Leiser and Chuck Gormley
Fadelu T, et al. Abstract 3517. Scheduled for presentation at: ASCO Annual Meeting; June 2-6, 2017; Chicago.
Disclosure: The NCI, NIH and Pfizer funded this study. Fadelu reports no relevant financial disclosures. Please see the abstract for a list of all other researchers’ relevant financial disclosures. Hayes reports research funding to his institution from AstraZeneca, Eli Lilly, Janssen, Merrimack Pharmaceuticals/Parexel International Corporation, Pfizer and Puma Biotechnology; honoraria from Eli Lilly; stock or other ownership in InBiomotion and OncoImmune; travel, accommodations or expenses from Janssen; and patents, royalties or other intellectual property with Janssen.