Evaluation of Chemotherapy-Induced Severe Myelosuppression Incidence in Obese Patients With Capped Dosing

PURPOSE: Clinicians typically cap an obese patient's chemotherapy regimen as a result of concern for excessive toxicity, without adequate clinical evidence. The purpose of this study was to evaluate the incidence of grade 3 or 4 myelosuppression in obese patients versus nonobese patients with capped dosing on the basis of body surface area (BSA). METHODS: A retrospective chart review was conducted comparing obese patients (body mass index BMI ≥ 30 kg/m(2)) with capped dosing who received capped chemotherapy doses at a BSA of 2.2 m(2) with nonobese (BMI < 25 kg/m(2)) patients with lung, colorectal, or hormone-refractory prostate cancer. RESULTS: Forty-one obese patients with capped dosing and 244 nonobese patients were included. The obese patient group received on average significantly more cycles of chemotherapy (6 v 4 cycles) compared with the nonobese group. The overall incidence of any chemotherapy-related toxicity was 34% in the obese patient group, compared with 42% in the nonobese patient group (P = .356). The incidence of grade 3 or 4 myelosuppression was lower, but not statistically significant, in obese patients with capped dosing compared with the nonobese patient group (22% v 27%; P = .493). CONCLUSIONS: Overall, obese patients with capped dosing experienced a lower incidence of severe myelosuppression and tolerated more cycles of chemotherapy compared with nonobese patients. The better tolerability of chemotherapy in obese patients with capped dosing suggests that there is room to increase the dose in obese patients above the nationally recognized BSA cap of 2.0 m(2), especially in early-stage lung or colon cancers in which the intention of treatment is curative.