Toxic effect of chemotherapy dosing using actual body weight in obese versus normal-weight patients: a systematic review and meta-analysis

Many oncologists reduce chemotherapy doses in obese patients due to fear of excess toxic effect from very large weight-based calculations. While recent guidelines advise against this practice, quantitative summarization of the supporting evidence is not available. We systematically identified studies that compared toxic effect or survival outcomes between obese and normal-weight adults receiving chemotherapy dosed by actual body weight (ABW). We pooled odds ratios (OR) and 95% confidence intervals (CI) using random-effects models. Of 5490 records screened, 12 studies representing 9314 relevant patients met inclusion criteria. The large majority of reported toxic effect and survival outcomes did not statistically differ between obese and normal-weight subjects. Exceptions included five studies in which one or more toxic effect or survival outcomes statistically favored obese patients, and one study that statistically favored normal-weight patients. Pooling usable data, rates of toxic effects were similar or lower in obese patients (grade 3/4 hematologic toxic effect: OR 0.73, CI 0.55-0.98, 4 studies; grade 3/4 nonhematologic toxic effect: OR 0.98, CI 0.76-1.26, 3 subgroups; any grade 3/4 toxic effect: OR 0.75, CI 0.65-0.87, three studies). Obese patients receiving chemotherapy based on ABW experience similar or lower rates of toxic effects compared with normal-weight patients, and survival outcomes do not differ.