Ryan Chiao, Senior Photographer

Researchers at the Yale Cancer Center have found that diet and fitness interventions in early-stage breast cancer patients may improve their outcomes.

Melinda Irwin, deputy director of the Yale Cancer Center and a senior author of the study, has dedicated her life to cancer prevention research. While investigating various types of cancer, Irwin has observed the challenges that patients face in adhering to chemotherapy — a common cancer treatment that has many adverse side effects, including hair loss, weight gain and fatigue. These side effects can be so severe that some patients stop seeking treatment.

“Physicians hear from women all the time that they wish they had better guidance and tools to help them through chemotherapy, especially to ward off side effects like fatigue, neuropathy and changes in body weight,” Irwin said.

According to Irwin, chemotherapy adherence is crucial to improving breast cancer treatment odds, and choosing to halt such therapy could have substantial — even fatal —  repercussions. 

Irwin and her research team sought to find lifestyle changes that could improve patients’ quality of life and encourage them to stick to chemotherapy.

“We set out 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 easier than usual care,” Irwin said. “The primary and secondary aims of the study were examining the effect of our intervention on chemotherapy completion and pathological complete response.”

The study followed 163 breast cancer patients receiving chemotherapy. Eighty-six did not change lifestyle habits, while 87 patients followed new exercise and diet routines. These patients walked for over 150 minutes per week and followed a plant-based diet with few added sugars and processed foods, following the guidelines of the Healthy Eating Index. Ultimately, the researchers tracked how well patients adhered to chemotherapy and the cancer’s resulting remission. The study measured the adherence to chemotherapy in RDI, or relative dose intensity, and the remission or improvement of cancer in pCR, pathological complete response.

Irwin and her team found that over 53 percent of the patients with new lifestyle routines saw their pCR improve, as compared to 28 percent of women in the control group, even though both groups had similar rates of chemotherapy adherence.

“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),” Tara Sanft, a medical oncologist at Smilow Cancer Hospital and the head researcher of the study, wrote in an email to the News. “This surprised us because the observational literature has shown that about 25 percent of patients and in some studies more than 25 percent are not able to complete their chemotherapy as prescribed.”

With the study’s surprising outcomes, the team hopes to further examine how diet and exercise interventions can improve a chemotherapy patient’s quality of life. Moreover, they want to explore how adherence studies can be applied to other cancer therapies.

“We are now examining the effect of the intervention on adherence to endocrine therapy — aromatase inhibitors and tamoxifen — as we know adherence is a challenge due to side effects,” Irwin wrote to the News. “We will also look into the pCR 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.”

Frank Horrigan ’26, who worked with an oncologist in Washington, D.C., over the summer, is also excited about the prospect of further research. 

The hospital where he worked had a significant population of low-income patients, and for these people, adherence is not always about choice.

“The treatment for chemotherapy is tough on patients, and the continued research of interventions like diet and fitness will definitely improve the experience and outcomes of patients,” Horrigan said. “There are so many other factors of patients’ lives that prevent them from staying on chemotherapy or even receiving the treatment.” 

Horrigan also told the News that he believes the research may contribute to “future
studies on addressing those social and economic barriers via hospital-sponsored programs.”

Irwin, too, is interested in the study’s policy implications. With increasing evidence of how diet and fitness changes can lead to improved outcomes, Irwin hopes to help health centers create intervention programs that implement these changes.

“Given the numerous benefits of healthy eating and physical activity, we need to better understand how to offer programs to our patients as standard of care and to make sure these programs are reimbursed,” Irwin wrote to the News.

The American Cancer Society estimates 297,970 new breast cancer cases in the United States in 2023.