Overweight cancer patients receiving immunotherapy treatments live more than twice as long as lighter patients, but only when dosing is weight-based, according to a study by cancer researchers at UT Southwestern Medical Center.

The findings, published in the Journal for ImmunoTherapy of Cancer, run counter to current practice trends, which favor fixed dosing, in which patients are given the same dose regardless of weight. The study included data on nearly 300 patients with melanoma, lung, kidney, and head and neck cancers over five years. Overweight patients were considered those with a body mass index, which accounts for height and weight, of 25 or more.

The researchers found that overweight patients did better with weight-based dosing, while lighter patients did better with fixed-dose immunotherapy. With weight-based dosing, overweight patients lived an average of more than 20 months compared with less than 10 months for lighter patients. With fixed dosing, both groups had similar outcomes, living an average of 16 months.

"Even when we accounted for differences in tumor and treatment types, overweight patients lived twice as long as smaller patients if they received weight-based dosing. However, there was no difference if they received fixed-dose immunotherapy," said senior author David Gerber, M.D., professor of internal medicine within the division of hematology and oncology at UT Southwestern, and associate director of clinical research in the Harold C. Simmons Comprehensive Cancer Center.

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