Background: 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.
Materials and methods: 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.
Results: 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).
Conclusions: 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.
Keywords: chemotherapy; dosing; obesity; survival; toxic effect.