This is the conclusion of a new study due to be presented at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting, which is being held in Chicago, IL, next month.
The new study, however, suggests that regular consumption of tree nuts may lower the likelihood of cancer recurrence following treatment for stage III colon cancer and improve patient survival.
Cashew nuts, hazelnuts, walnuts, almonds, and pecans are all tree nuts, and a number of studies have documented their potential health benefits.
One study published in 2014, for example, associated tree nut intake with reduced risk of obesity and metabolic syndrome, while other research has associated tree nut consumption with better heart health.
For this latest study, lead author Dr. Temidayo Fadelu, of the Dana Farber Cancer Institute in Boston, MA, and colleagues set out to investigate whether overall nut intake or tree nut consumption alone might benefit patients with colon cancer.
Colon cancer patients should include tree nuts as part of a healthful diet
To reach their findings, the researchers analyzed the data of 826 patients with stage III colon cancer. The patients were part of a Cancer and Leukemia Group B clinical trial, which began in 1999, and they had completed chemotherapy.
For the trial, patients were required to complete a dietary questionnaire. Dr. Fadelu and colleagues used this information to calculate the patients' weekly intake of nuts, and whether this was associated with the risk of colon cancer recurrence and survival.
Compared with patients who did not eat nuts, those who consumed at least 2 ounces of nuts every week were found to have a 42 percent lower risk of colon cancer recurrence and a 57 percent reduced risk of death.
However, on closer investigation, the researchers found that only tree nut consumption offered benefits; the risk of colon cancer recurrence was 46 percent lower for patients who ate at least 2 ounces of tree nuts each week, while the risk of death was 53 percent lower.
Consumption of peanuts or peanut butter was not associated with a significant reduction in cancer recurrence or death.
Based on their results, Dr. Fadelu and colleagues suggest that patients with colon cancer may benefit from including tree nuts in their diet.
"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.
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."
Dr. David Hayes, ASCO president
In future studies, the researchers plan to investigate how tree nut consumption impacts the risk of cancer recurrence and death for patients in the later stages of colon cancer.
"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," adds Dr. Fadelu.