Eating certain kinds of tree nuts, such as almonds, pecans, walnuts, hazelnuts and cashews, has been linked to a dramatically lower risk of colon cancer recurrence, researchers said Wednesday.
The observational study involved 826 patients who had undergone treatment for stage III colon cancer, typically including surgery and chemotherapy.
Such patients -- whose cancer has not spread elsewhere in the body -- have a 70 percent chance of surviving three years after treatment.
Some 19 percent of patients consumed two or more ounces of all types of nuts per week.
These nut-eaters saw a 42 percent lower chance of cancer recurrence -- and a 57 percent lower chance of death than patients who did not eat nuts after completion of their cancer treatment, said the report, released ahead of the American Society for Clinical Oncology (ASCO) annual meeting, held in Chicago next month.
When researchers looked only at tree nut consumption, the chance of recurrence was 46 percent lower and the chance of death was 53 percent lower for those who ate at least two ounces per week, compared to people who did not eat nuts.
Peanuts and peanut butter -- the most commonly consumed nuts in the United States -- did not appear to have any significant effect.
"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, 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."
Eating nuts should not be considered a substitute for standard chemotherapy and other treatments for colon cancer, experts said.
"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," said ASCO president Daniel Hayes.
Researchers cautioned that the study was observational in nature and did not prove cause and effect.
A separate study discussed Wednesday ahead of the Chicago cancer conference involved 992 people whose colon cancer had not spread. It showed that following a Mediterranean diet and exercising reduced their risk of dying prematurely by 42 percent and also cut their chances of seeing their colon cancer return.