Relationship between toxicity and obesity in women receiving adjuvant chemotherapy for breast cancer: results from cancer and leukemia group B study 8541.

PURPOSEWe examined data from a large clinical trial to determine if chemotherapy dosing according to actual body weight places obese patients at greater risk of toxicity.PATIENTS AND METHODSCancer and Leukemia Group B (CALGB) study 8541, a randomized study of schedule and dose of adjuvant cyclophosphamide, doxorubicin, and fluorouracil (CAF) for stage II breast cancer patients with positive regional lymph nodes, provided data on 1,435 women for analysis. Using body-mass index (BMI), we classified a woman as obese if her BMI was > or = 27.3 kg/m2; doses were considered weight-based if within 5% of values calculated using actual weight. Our primary analysis concerned toxicity risks during cycle 1.RESULTSAmong women who received weight-based doses of the most dose-intensive CAF regimen, 47% of obese and 51% of nonobese women experienced severe hematologic toxicity (grade > or = 3) during cycle 1 (P = .51, two-tailed). The overall risk ratio (obese v nonobese) of treatment failure among women who received wei...