Muscle Mass Could Predict Chemo Side Effects in Early Breast Cancer, Study Reports

Muscle Mass Could Predict Chemo Side Effects in Early Breast Cancer, Study Reports

Early-stage breast cancer patients with low muscle mass are at increased risk of experiencing serious chemotherapy side effects and twice as likely to be hospitalized, according to a study.

The findings suggest that both muscle quantity and quality could be used to predict which patients are at high risk of toxic effects from chemo. And the measures could replace body surface area in determining appropriate chemotherapy doses, the researchers said.

The study, “Body Composition as a Predictor of Toxicity in Patients Receiving Anthracycline and Taxane Based Chemotherapy for Early Stage Breast Cancer,” was published in the journal Clinical Cancer Research.

Chemotherapy is an essential component of treatment for early breast cancer, especially in patients with HER2 positive or triple-negative tumors. Yet, chemotherapy toxicity is a major issue. Nearly 20% of patients experience non-hematological — or non-blood — toxicities, and 40% hematological toxicities.

Doctors say the challenge is predicting which patients are likely to experience chemotherapy side effects, and to what extent.

Researchers at the University of North Carolina (UNC) Lineberger Comprehensive Cancer Center developed a tool to help doctors identify patients at high risk of side effects that are so severe that they can lead to hospitalization.

Shlomit Strulov Shachar, MD, and his colleagues reviewed the medical records of 151 patients treated for early breast cancer at the N.C. Cancer Hospital between 2008 and 2013. Fifty patients, or 33%, experienced serious chemotherapy toxicities. They included gastrointestinal complications such as nausea or vomiting, depletion of important blood cells, and nerve damage in arms or legs.

The team examined the computerized tomography (CT) images of patient before treatment to estimate their muscle and fat composition. They measured muscle quality and quantity, including indirect fat content, to develop a body composition yardstick that they termed “skeletal muscle gauge.”

Patients with low muscle quality and quantity were at higher risk of experiencing blood-related toxicities, gastrointestinal side effects, and neuropathy, the team found. The same patients were also twice as likely to be hospitalized.

The Skeletal muscle gauge that the research team developed was a better predictor of treatment-related toxicities than body composition measures such as body mass index.

Chemotherapy dosing is based on body surface area, a measure that accounts for height and weight, but not for other body-composition characteristics. The research team’s findings suggest that measuring muscle composition may not only help doctors predict which patients will experience chemotherapy toxicities, also help physicians determine appropriate drug doses.

“Hospitalization is a terrible thing for patients, especially for older patients after chemotherapy,” Hyman B. Muss, MD, a co-author of the study, said in a press release. “We need better ways of predicting who might be hospitalized for treatment side effects. If we can give a little less dose initially, we might be able to lower toxicities without sacrificing effectiveness. By improving the therapeutic index we can retain the benefits while minimizing the risks of treatment,” said Muss, Mary Jones Hudson Distinguished Professor and director of the UNC Lineberger Geriatric Oncology Program.

“For me, as a physician in the clinic, it’s very troubling when patients get toxicity from therapy,” Shachar said. “We need to deliver the best therapies we can with less toxicity. We need to think carefully about how to dose patients other than relying on just height and weight.”

Further studies are needed to investigate how the metrics can be used to dose chemotherapy more precisely, researchers said. The goal is to reduce toxicity while maintaining the treatment’s effectiveness.

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