Toxicity and tolerability of adjuvant breast cancer chemotherapy in obese women

Abstract

The purpose of this study was to compare toxicity rates and types between obese and non-obese women during adjuvant chemotherapy for breast cancer, adjusting for regimen type and received dose. We conducted a retrospective cohort study of 537 women receiving chemotherapy, initially treated between 2007 and 2010 at two tertiary hospitals in Brisbane, Australia. Demographic, chemotherapy and toxicity data were extracted from patient charts and analyzed using multivariate logistic regression. Three hundred and seventy-four women were eligible for inclusion. Obese women (body mass index (BMI) > 30 kg/m(2); mean age 52.58 ± 9.49) were older than non-obese women (BMI ≤ 29.9 kg/m(2); mean age 50.19 ± 11.15, P = 0.05) and had more comorbidities (P < 0.01). After adjustment for potential confounders, obesity was not statistically related to chemotherapy-related admission risk (OR 1.27; 95 % CI 0.78-2.09) or febrile neutropenia risk (OR 0.56; 95% CI 0.28-1.21). However, obese women received chemotherapy with proportionally lower mean relative dose intensity than non-obese women (94 vs. 97% of reference dose, P = 0.03). Eighteen (15.8%) obese and zero non-obese women (P < 0.01) had their chemotherapy dose capped at an arbitrary body surface area. Compared with non-obese women, obese women receive different chemotherapy regimens and relatively lower chemotherapy doses. There was no significant evidence of increased toxicity among obese women with either full or adjusted chemotherapy doses. Full body surface areas-based dosing appears to be tolerated as well in obese as in lean women.