5 minutes reading time (988 words)

Prescribing a Healthy Diet and Exercise for Breast Cancer With Neil Iyengar, MD

Neil Iyengar, MD.

Patients with breast cancer can derive significant benefits from eating well and staying physically active during their treatment. In his previous interview with i3 Health, Neil Iyengar, MD, a medical oncologist at Memorial Sloan Kettering Cancer Center, explained the roles that nutrition and exercise can play in the prevention and treatment of breast cancer. In this second installment, Dr. Iyengar discusses the personalized strategies that are most likely to benefit patients. In addition, he offers advice to oncologists regarding how to help patients with breast cancer to incorporate good nutrition and exercise as important facets of their treatment and post-treatment living.

How can nutrition and exercise plans be personalized to suit the individual needs of patients with breast cancer?

Neil Iyengar, MD: Personalization of treatment is very important. The most successful strategies are based on understanding an individual's biology and specific type of breast cancer and then matching that to an appropriate exercise or nutrition prescription. Right now, we have evidence that only supports broad categorization. We know that certain chemotherapies, for example, can increase the risk of cardiotoxicity, or damage to the heart. Because aerobic exercise can be helpful in reversing that damage, I would recommend aerobic activity for patients who are exposed to cardiotoxic chemotherapy. Because patients who are treated with certain types of hormone therapies can be at risk for osteoporosis, I would recommend that these patients begin exercise programs that improve bone health, such as weight-bearing exercises or even resistance training. This approach is a little better and more personalized than just telling everybody that they should exercise, but it's still based on broad characterization.

We currently have several clinical trials in which we're creating exercise prescriptions by bringing patients in for exercise testing, measuring their fitness, and then developing a prescription program. These trials will help to determine whether that type of personalized approach will ultimately be helpful for prolonging survival and reducing the risk of recurrence. As far as nutrition—apart from the broad recommendations for eating a plant-centered diet, consuming fewer processed foods, and increasing fiber intake—there still isn't enough data to recommend a specific diet to a specific patient, but that's what we're working on.

There are a couple of upcoming clinical trials in which we will be focusing on the genes that are expressed in the breast tissue. We will test how dietary changes, such as a plant-based diet, might modify that gene's expression. That will help narrow down a more personalized approach to nutrition. There is also data suggesting that certain diets, such as low carbohydrate diets, might benefit specific genetic mutations in metastatic breast cancer tumors. However, the same diet may not be beneficial for a different type of tumor. What I'm telling my patients right now is only based on observational data, but I think we will eventually get to a place where we can make personalized nutrition recommendations based on an individual's biology and type of cancer.

Do you have any words of advice for community oncologists and other members of the supportive care team as they work with patients with breast cancer?

Dr. Iyengar: As we continue to learn about the importance of diet and exercise in cancer care, I strongly advise that clinical practices incorporate a multidisciplinary approach. Having a nutritionist on the team can be extremely valuable. Because the oncologist may not be trained or may not have the time to review a patient's diet and suggest modifications, a nutritionist would be incredibly helpful for providing those recommendations.

From an exercise perspective, it is important for the oncologist to at least have a discussion with the patient to emphasize that staying active during therapy is critical for improving quality of life and potentially reducing the risk of recurrence. If the oncologist is the one stressing this, it really emphasizes the importance of physical activity and nutrition during and after cancer therapy. Oncologists can look to the American Society of Clinical Oncology (ASCO) guidelines or other specific recommendations for moderate to vigorous activity and resistance training for their patients.

Ultimately, we shouldn't be recommending very narrow and restrictive diets or exercise programs for our patients. We need to be thinking more about broad lifestyle changes and dietary patterns that are compatible with a person's life. A patient may be motivated to make some extreme changes right after a cancer diagnosis, but whatever changes are made should be easily maintainable in the long run. It is therefore very important to work with the patient to determine the type of lifestyle pattern that works best for him or her while still adhering to the guidelines and promoting adequate physical activity and a healthy diet. There's a lot to accomplish in a medical oncology visit, and that's why a multidisciplinary approach is truly essential to optimal oncology care.

About Dr. Iyengar

Neil Iyengar, MD, is a medical oncologist in the Breast Medicine Service at Memorial Sloan Kettering Cancer Center in New York. He also leads the Tri-Institutional Obesity, Cancer and Metabolic Diseases Working Group. Dr. Iyengar has led numerous clinical trials investigating the association between cancer and metabolic health, including the roles of nutrition and exercise in the treatment of patients with breast cancer. His research focuses on the development and implementation of dietary strategies, exercise plans, and other lifestyle interventions to improve outcomes in patients with breast cancer.

For More Information

Iyengar NM, Arthur R, Manson JE, et al (2019). Association of body fat and risk of breast cancer in postmenopausal women with normal body mass index: a secondary analysis of a randomized clinical trial and observational study. JAMA Oncol, 5(2):155-163. DOI:10.001/jamaoncol.2018.5327

Runowicz CD, Leach CR, Henry NL, et al (2016). American Cancer Society/American Society of Clinical Oncology breast cancer survivorship care guideline. J Clin Oncol, 34(6): 611-635. DOI:10.1200/JCO.2015.64.3809

Transcript edited for clarity. Any views expressed above are the speaker's own and do not necessarily reflect those of i3 Health. 

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