Impact of body mass index on the clinical outcomes of patients with HER2-positive metastatic breast cancer.

Abstract Background Overweight and obesity are associated with an increased risk of developing many types of cancer, including breast cancer. Moreover, increased body mass index (BMI) seems to be associated with a worse prognosis in patients with HER2-positive early breast cancer. However, little is known about the impact of BMI on the clinical outcomes of HER2-positive metastatic breast cancer (MBC). Methods This was a multicenter retrospective cohort study including 329 consecutive patients with HER2-positive MBC treated with first-line trastuzumab-based regimens. BMI at the time of MBC diagnosis was collected. World Health Organization BMI categories were used: underweight 2 , overweight 25–29.9 Kg/m 2 , and obese ≥30 Kg/m 2 . The analyses were conducted using two categories: BMI  Results Overall, 176 (53.5%) patients were normal/underweight and 153 (46.5%) overweight/obese. Median PFS was 14.8 months in BMI  Conclusions BMI does not seem to be associated with clinical outcomes in HER2-positive MBC patients.