Dosing of chemotherapy for solid tumors based on ideal body weight versus actual body weight: Review of a military oncology clinic’s practice.

Abstract

e17575 Background: Dose-reductions or “capping” of the body surface area (BSA) at 2.0m2 for chemotherapy due to obesity has been widely practiced throughout oncology due to the concerns about AE in obese patients. In 2012 ASCO published guidelines recommending that full weight-based dosing of chemotherapy be used. This retrospective review was undertaken to evaluate the dosing practices at a major U.S. Army oncology clinic. Methods: Retrospective, random sampling of patients with breast, lung, gastrointestinal and testicular cancer and lymphoma treated at a tertiary military medical center within the last three years. Basic demographic data, cancer type, stage, actual and ideal BSA , incidence of dose-reduction, hematologic data before and after cycle 1, incidence of grade 3-4 toxicity and use of granulocyte-colony stimulating factor was recorded. Results: 231 patients (61.9% female, 38.1% male) were included in the analysis (breast 36.4%, lung 19.5%, GI 21.2%, testicular 6.5%, lymphoma 16.5%). The majority of patients were white, 70.6%, with asian, black, hispanic and other making up 2.6%, 13.4%, 1.7% and 11.7% respectively. Seventy-eight had a BSA >2.0m2. No incidences of dose-reduction were identified. Analysis did not show a correlation between differences in actual vs. ideal BSA and toxicity. When other variables were considered, there was a statistically significant inverse relationship between age and grade 3-4 toxicity (p=0.02) although this was deemed clinically insignificant (coefficient of determination <0.25). Conclusions: In a retrospective review of chemotherapy dosing practices in a major military medical center, we found no cases of dose-reduction based on obesity. There was also no significant increased toxicity when patients were dosed according to actual vs ideal body weight in keeping with previously published literature. There was a significant inverse relationship between age and grade 3-4 hematologic toxicity.