Tara B. Sanft, MD, on How Diet and Exercise May Affect Completion of Chemotherapy for Breast Cancer

We know completing chemotherapy as prescribed is important for cancer outcomes. We also know that adopting healthy diet and exercise is important, both for cancer prevention and, in certain cancers, can improve cancer-related survival. The healthy diet and exercise guidelines include eating a predominantly plant-based diet and exercising with moderate intensity exercise at least 150 minutes per week, and performing two strength training sessions per week. Our study, the Lifestyle, Exercise, and Nutrition Study, randomized women who were not meeting these guidelines to a healthy diet and exercise intervention based on the Diabetes Prevention Protocol and adapted using the cancer-related guidelines as well versus usual care, which is referral to our survivorship clinic and dieticians and exercise programs at request by the patient. Our primary outcome was looking at the relative dose intensity, or the actual amount of chemotherapy received compared to that which was prescribed. The intervention group received a year-long intervention of 16 sessions administered by a registered dietician who was certified, specialized in oncology, and also had exercise counseling training. The control group were followed at baseline post-chemotherapy. What we found was that both groups completed chemotherapy at very high rates, with both groups approaching about 93% completion rates. This is higher than what we had found in the literature before. We also found that the number of dose delays and reductions were similar between the two groups. When we looked at the intervention group, in particular, and we looked at if they were meeting the actual recommendations, that is 150 minutes per week and a high consumption of fruits and vegetables, we found that women who were able to meet these guidelines or exceeded them, did have higher completion rates compared to those who didn't quite make those guidelines. So in summary, the women who made the highest number of changes or adhered the best did have better relative dose intensity and fewer dose reductions and delays. But when we took the entire intervention group and compared them to usual care, we did not find a statistically significant difference. In summary, both groups completed their chemotherapy as prescribed most of the time, and the intervention group significantly improved both their diet and physical activity during the course of the intervention. Those who were able to adopt the exercise and diet recommendations the best did have significant improvements in their completion rates and fewer dose reductions and delays compared to those who didn't adopt it as well.