Reducing Risk After Cancer: Healthy Lifestyle (and Tree Nuts)

Roxanne Nelson, BSN, RN

May 18, 2017

Patients with cancer often ask what they can do to help themselves. New data from a long-running trial in patients with early-stage colorectal cancer confirm that following a healthy lifestyle reduces the risk for death from cancer. A companion analysis adds a new finding: So does eating tree nuts.

The new findings come from questionnaires completed by patients with stage III colorectal cancer during and after adjuvant chemotherapy.  

"We found that patients who had a healthy body weight; engaged in regular physical activity; ate a diet high in vegetables, fruits, [and] whole grains and low in processed meats and red meats; and drank small to moderate amounts of alcohol had longer disease-free and overall survival than patients who did not," said lead study author, Erin Van Blarigan, ScD, assistant professor of epidemiology and biostatistics, University of California, San Francisco.

Following a healthy lifestyle cut the risk for death by 42%, and adding moderate alcohol consumption to the analysis further reduced the risk for death, by 15%.

Dr Van Blarigan was speaking at a presscast preceding the annual meeting of the American Society of Clinical Oncology (ASCO), at which the full results will be presented.

The new results come from an analysis of data collected during the CALGB 89803 trial. This trial compared various adjuvant chemotherapy regimens; results were published 10 years ago (J Clin Oncol. 2007;25:3456-3461).

Lifestyle was assessed at two different time periods during the study period by using validated surveys. A scoring system was used to quantify adherence to guidelines issued by the American Cancer Society (ACS) (range, 0 to 6; the higher the score, the more healthy the behaviors).

Alcohol consumption is included in the ACS guidelines for cancer prevention, but not for cancer survivors, so Dr Van Blarigan explained that they evaluated the scoring with and without alcohol use.­­­­­­

At a median follow-up of 7 years, there were 335 recurrences and 299 deaths (43 without recurrence).

The researchers then compared the outcomes for patients with the highest scores for adhering to the healthy lifestyle guideline (5 to 6 points; n = 91 [9%]) with outcomes for patients who scored lowest for adherence to the guidelines (0 to 1 point; n = 262 [26%]). They found a 42% lower risk for death (hazard ratio [HR], 0.58; P for trend = .01) and a trend toward improved disease-free survival (DFS) (HR, 0.69; P for trend = .03) for the patients who adhered most closely to the healthy lifestyle recommendations.  

When the analysis included alcohol in the score, the adjusted HRs for patients with a score of 6 to 8 points (n = 162 [16%]) compared with those whose score was to 0 to 2 points (n = 187 [91%]) were 0.49 for overall survival (P for trend = .002), 0.58 for DFS (P for trend = .01), and 0.64 for relapse-free survival (P for trend = .05).

"Our research team is conducting clinical trials to evaluate the feasibility and acceptability of digital health lifestyle interventions, such as Fitbit, for colorectal cancer patients," said Dr Van Blarigan. "If our interventions are acceptable and useful to patients, we will test their impact on risk of cancer recurrence and mortality in future studies."

The study does have some limitations because the findings rely on patients' recall of their own behavior, "but the bottom line is that ACS guidelines and others recommend healthy behaviors because they are healthy for you," commented Richard L. Schilsky, MD, chief medical officer of ASCO.

Tree Nuts Lower Mortality and Recurrence

In a related study that used the same cohort of patients from the CALGB 89803 trial, researchers found that regular consumption of tree nuts also was associated with a lower risk for colon cancer recurrence and improved overall survival.

Among the 826 patients included in this analysis, the results showed that those who consumed 2 or more ounces of nuts per week had a 42% lower risk for disease recurrence and a 57% lower mortality risk compared with those who did not eat nuts. 

But a secondary analysis, explained lead author, Temidayo Fadelu, MD, a clinical fellow in medicine at Dana Farber Cancer Institute, Boston, Massachusetts, showed that the benefit of nut consumption was limited to tree nuts — the  association was not significant for peanuts and peanut butter.

The biologic mechanism is currently unknown but is likely related to the effect of nuts on insulin resistance, he pointed out. "These findings contribute to evidence of protective benefit of dietary and lifestyle factors in colon cancer."

Other observational studies have suggested that increasing nut intake is associated with lower risk for type 2 diabetes, metabolic syndrome, and insulin resistance.

Improved DFS

Dr Fadelu and his colleagues assessed associations of nut consumption with cancer recurrence and mortality, with a primary endpoint of DFS.

They found that compared with patients who abstained from eating nuts, those who consumed at least 2 servings of nuts per week had an adjusted HR of 0.58 (P for trend = .03) for DFS and 0.43 (P for trend = .01) for overall survival.

The authors also found that on subgroup analysis, the significant association applied only to consumption of tree nuts: HR of 0.54 (P trend = .04) for DFS and  0.47 (P for trend = 0.04) for overall survival.

Of note, they found that the association of nut consumption with improved outcomes was maintained across common genomic alterations (microsatellite instability, KRAS mutation, BRAF mutation, and PIK3CA mutation).

Dr Schilsky noted that the study found that eating 2 servings of tree nuts per week was associated with more favorable outcomes, "but whether this is due to eating the nuts or whether this is due to some other behavior for which eating tree nuts is a surrogate is unclear."

"However, there is a growing body of evidence that eating tree nuts is generally good for you, and this is another piece of data pointing in the same direction," he told Medscape Medical News.

Does Not Replace Treatment

Commenting on both studies, ASCO President, Daniel F. Hayes, MD, noted the data show that "you have a pretty good chance of surviving if you have colon cancer and that healthy people live healthier."

However, he cautioned that these results do not mean that lifestyle can replace treatment and said that patients must not forgo the standard of care in treating their disease.

"Nobody wants to undergo chemotherapy," said Dr Hayes. "We understand that, but chemotherapy clearly saves lives."

"People should not interpret these two abstracts as suggesting that if you live a healthy lifestyle and you eat tree nuts, you don't need to take the chemotherapy that your oncologist would recommend," he added. "That's a very dangerous interpretation."

Dr. Van Blarigan's study (abstract 10006) was funded by the National Cancer Institute of the National Institutes of Health; Dr. Fadelu's study (abstract 3517) was funded by the National Cancer Institute and Pfizer. Dr Van Blarigan and Dr Fadelu have disclosed no relevant financial relationships, although multiple coauthors from both studies have disclosed relationships with industry. Dr Hayes reports stock and other ownership interests with OncoImmune and InBiomotion; honoria from Lilly; research funding (institutional) from  Janssen, AstraZeneca, Puma Biotechnology, Pfizer, Lilly, and Merrimack/Parexel; patents, royalties and other intellectual property with royalties from licensed technology to Janssen Diagnostics regarding circulating tumor cells; and travel, accommodations, and expenses from Janssen Diagnostics

American Society of Clinical Oncology Annual Meeting. Abstracts 10006 and 3517, to be presented June 2 and June 3, 2017, respectively.

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