Do exercise and a healthy diet improve outcomes for cancer patients? A new study investigated whether such an intervention helps patients with Stages I-III breast cancer undergoing initial chemotherapy. The data showed that women undergoing the intervention-which was a home-based exercise and nutrition program with counseling sessions delivered by oncology-certified registered dietitians-had similar chemotherapy completion rates at the end of initial therapy as women undergoing usual care. However, women who underwent the intervention saw improvements in diet quality, physical activity levels, and pathological complete response. That last outcome was a surprise for the study authors and others (J Clin Oncol 2023; doi: 10.1200/JCO.23.00871).
"There are many reasons to encourage a healthy diet and regular exercise in women with breast cancer requiring chemotherapy. This study shows it may increase pathological complete response. Nonpharmacologic interventions are worthy of great attention and appropriately powered trials," Kathy D. Miller, MD, Senior Deputy Editor of the Journal of Clinical Oncology, noted in a relevance statement published with the study.
Melinda L. Irwin, PhD, MPH, the Susan Dwight Bliss Professor of Epidemiology and Associate Dean of Research at Yale School of Public Health, and Deputy Director of Population Sciences at Yale Cancer Center, and Tara Sanft, MD, Associate Professor of Medicine (Medical Oncology) and Medical Director of the Survivorship Clinic at Yale School of Medicine, shared their thoughts about the research findings.
1 What led to conducting this research now?
Sanft: "We hear from women all the time that they wish they had better tools to help them through chemotherapy, especially tools to ward off side effects like fatigue and weight gain. We set about to study if a healthy diet and exercise intervention during chemotherapy for early-stage breast cancer would help with side effects and allow women to complete chemotherapy more easily than usual care."
Irwin: "To our knowledge, no other study has combined a healthy diet intervention delivered by registered dietitians with exercise during chemotherapy to examine chemotherapy completion rates."
Sanft: "We looked at a measure of chemotherapy completion called relative dose intensity (RDI). This is a ratio of how much chemotherapy a patient received compared to what was prescribed. If a patient receives all the chemotherapy exactly as prescribed, the RDI would be 100 percent. What often happens is doses are modified (reduced or delayed) to lessen side effects, including fatigue and neuropathy, for instance, so patients might not complete the chemotherapy as prescribed but instead might complete 90 percent of it. We know RDI of less than 85 percent is associated with poorer outcomes. We also examined other prognostic factors such as pathologic complete response in women undergoing neoadjuvant chemotherapy."
Irwin: "We based the intervention on the Lifestyle, Exercise, and Nutrition (LEAN) study, which is a healthy diet and exercise intervention taking elements of the American Cancer Society and World Cancer Research Fund/American Institute for Cancer Research healthy lifestyles guidelines for cancer survivors, along with the Diabetes Prevention Program. We adopted those for breast cancer patients to specifically address issues unique to this population."
2 What were key research findings and implications?
Sanft: "We found both groups (intervention and control) were able to complete the chemotherapy at very high rates, with no difference between the groups in RDI (93% in both groups). We did find the intervention group had a higher rate of pathological complete response compared to usual care, which is an interesting finding that deserves additional investigation.
"We found women in the intervention had high rates of adherence to the diet and exercise counseling sessions. It is important to point out that eligible patients needed to be sedentary and not meeting dietary guidelines at baseline. This intervention significantly improved physical activity (increased minutes/week), strength training (with 70% of women in the intervention group participating in strength training at end of chemotherapy), and diet quality (improved fiber and fruits/vegetables intake). This finding is something to celebrate as it illustrates adopting healthy lifestyle changes during chemotherapy is possible even for those who are not practicing them at diagnosis. It is not too late for oncologists to recommend these healthy behaviors to patients."
Irwin: "We will next study the secondary outcomes at 1 and 2 years after diagnosis. These include adherence to endocrine therapy, another treatment that is critical to survival outcomes yet can be difficult to complete based on side effects, some of which are directly impacted by healthy behaviors. We will also look into the pathological complete response finding. This is exciting and needs further exploration as this was not the primary outcome of our study. This may indicate other factors are at play other than chemotherapy completion."
3 What is the bottom-line takeaway about this research?
Sanft: "The bottom line is a healthy diet and exercise intervention led to significant improvements in diet quality, physical activity, and pathological complete response rates in women undergoing chemotherapy for early-stage breast cancer who were not meeting healthy lifestyle recommendations at diagnosis. While both groups had high (more than 90%) RDI, the intervention group had significantly higher pathological complete rates compared to usual care-a finding that must be validated in future studies."