Impact of body mass index on survival in women receiving chemotherapy for early breast cancer.

ABSTRACT

PURPOSE: The impact of elevated body mass index (BMI) on overall survival (OS) in patients receiving modern anthracycline-taxane chemotherapy for early breast cancer (EBC) has not yet been well established. The purpose of our study was to examine overall survival (OS) by BMI category in women with EBC receiving either doxorubicin (A), cyclophosphamide (C) + paclitaxel (P) or fluorouracil (F), epirubicin (E), cyclophosphamide (C) + docetaxel (D). METHODS: This was a retrospective cohort study in patients ≥ 18 years with resected stage I-III BC diagnosed between 2007 and 2017 in Ontario, identified through linkage of administrative databases. Patients were classified according to baseline BMI into underweight (< 18.5 kg/m2), normal (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (≥ 30 kg/m2) World Health Organization (WHO) categories. The primary outcome was OS. Univariable and multivariable analyses were used to examine the association between clinico-pathologic characteristics and OS among BMI categories. RESULTS: Our cohort included 11,601 women, of whom 3890 (33.5%) were normal weight, 3696 (31.9%) overweight, and 3847 (33.1%) obese. Median OS was 7.9 years. There were no statistically significant differences in OS according to BMI (p = 0.66) in the overall study cohort or among the BMI categories after adjusting for age, nodal status, stage, grade, ER and HER2 status for either AC-P or FEC-D- treated patients (p = 0.45 and p = 0.97, respectively). CONCLUSIONS: Our large population-based retrospective cohort analysis of EBC patients receiving adjuvant anthracycline-taxane chemotherapy found no significant impact of BMI on OS. Further investigation is warranted to confirm these findings in prospective patient cohorts.