There’s abundant evidence that diet and lifestyle factors drive the risk for developing certain cancers, notably colon cancer, explains Charles S. Fuchs, MD, MPH. These factors, he says, include diets high in red meat, diets with a high glycemic load, and being sedentary. However, he finds that the people most motivated by the literature linking poor lifestyle choices to cancer are not healthy people who are at risk, it’s the people who have cancer. “In fact, 75% of newly diagnosed patients with cancer believe there is a diet, lifestyle, or supplement that will improve their outcome,” he says. “What we’ve tried to do for years is to assess the effect of diet, not among people undiagnosed with cancer, but people who have been recently diagnosed with cancer.”

To address this, Dr. Fuchs and colleagues published a paper in the Journal of Clinical Oncology, with the aim of measuring the impact of diet and lifestyle habits on patient outcomes to determine if these factors can enhance the accuracy of predicting survival outcomes. They studied a cohort of patients across the United States and Canada with stage III colon cancer who had recently undergone a surgical resection, were believed to be disease-free, and who were receiving standard adjuvant therapy.

“At the time they received their adjuvant therapy post-surgery, we administered a questionnaire on diet, lifestyle, and supplements,” Dr. Fuchs says. The researchers administered the same questionnaire about a year later and followed patients for 7 years to see if there was there any particular diet or lifestyle that would either increase the likelihood of being cured of colon cancer or, alternatively, increase the likelihood of recurrence.

Refined Grains & Obesity Increased Risk of Recurrence

Among 1,024 patients, the researchers reported 394 disease-free survival (DFS) events and 311 deaths after median follow-up of 7.3 years. “We found that refined grains and obesity increase the likelihood of recurrence,” Dr. Fuchs notes. “We also observed that regular physical activity and vitamin D reduced the risk for recurrence. In clinical oncology, we typically look at the clinical and pathologic factors and put people into good risk, average risk, and poor risk categories based purely on those clinical factors. So, beyond the appropriate treatments for colorectal cancer, we observed that diet and lifestyle matter, which is really important for patients.”

The study team found that patients who took on a healthy lifestyle increased their likelihood of 5-year DFS by 6.3%, if they had good-risk features, by 21.4%, if they had average-risk features, and by 42.6%, if they had poor-risk features. “Our study delineates the impact of diet and lifestyle on DFS and overall survival beyond the influence of known clinical and pathologic factors,” Dr. Fuchs says. “The results suggest that patients and providers can leverage diet and lifestyle modifications to improve patient outcomes (Table).”  

Assess Patients’ Approach to Diet and Lifestyle

Since the data suggest that most patients with cancer are interested in making diet and lifestyle changes to improve their outcome, it is incumbent on practitioners to talk with patients about it, Dr. Fuchs points out, adding that the first step is to assess a patient’s current approach to diet and lifestyle. “If they are consuming an unhealthy diet, are sedentary, or having difficulties with weight control, this is a perfect opportunity to talk to them about making changes to improve their chances for a cure. It also empowers patients to have some say in how they’re going to take control of their lifestyle and patients are quite motivated.”

Dr. Fuchs and colleagues would like to see future research confirm these findings that suggest that lifestyle matters. “In addition, we really want to try to make this user-friendly,” he says. “Now that we have this ability to determine a healthy or unhealthy score, could we create an online tool that practitioners and/or patients could use, and then find out that if they were to take a healthier approach, what increment of cure would they gain? Beyond that, I’d love for scientists to discover what’s driving the biology and what new therapies we glean from these biologic insights.”