Obesity Heightens Chemotherapy Toxicity in Breast Cancer

The study was published on researchsquare.com as a preprint and has not yet been peer reviewed.

Key Takeaway

  • Chemotherapy toxicity is more severe in early-stage breast cancer among patients who are obese compared with those who are not.

Why This Matters

  • The findings point to the need for extra vigilance in monitoring chemotherapy toxicity in women with obesity.

Study Design

  • Overall, 286 women with stage I–III breast cancer completed toxicity surveys while undergoing chemotherapy.

  • The investigators compared the responses of 117 women whose body mass index (BMI) was ≥30 kg/m2 with those of 169 women whose BMI was <30 kg/mg2. They then calculated risk ratios (RRs) for various adverse events, adjusting for marital status and race.

Key Results

  • The obesity rate was 76% among Black women (23% of the study population) and 31% among White women.

  • Women with obesity rated an average of 6.9 side effects as being moderate, severe, or very severe, while women who were not obese reported an average of 5.5 such side effects (P = .003).

  • Women with obesity were at significantly greater risk for moderate, severe, or very severe fatigue (RR, 1.18), dyspnea (RR, 1.71), arthralgia (RR, 1.47), peripheral neuropathy (RR, 1.45), limb edema (RR, 1.84), and abdominal pain (RR, 1.75).

  • The researchers observed no significant differences between the two groups in dose delays, dose reductions, or hospitalizations during chemotherapy.

  • Greater symptom severity among women with obesity likely reflects higher chemotherapy doses and greater comorbidity burdens at baseline.


  • The sample was limited to patients who agreed to participate in a moderate exercise program during chemotherapy.

  • The sample also included a high proportion of women who had more than a college education.


  • The work was funded by the Breast Cancer Research Foundation of New York and the Kay Yow Foundation.

  • The investigators disclosed no relevant financial relationships.

This is a summary of a preprint research study, “Body Mass Index and Patient-Reported Measures of Function, Quality of Life and Treatment Toxicity in Women Receiving Adjuvant Chemotherapy for Breast Cancer,” led by Kirsten Nyrop of the University of North Carolina at Chapel Hill. The study has not been peer reviewed. The full text can be found at researchsquare.com.

M. Alexander Otto is a physician assistant with a master’s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who has worked for several major news outlets before joining Medscape and also an MIT Knight Science Journalism fellow. Email: [email protected].

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