Comparison of the prognostic value of different skeletal muscle radiodensity parameters in endometrial cancer

Recent data have shown that dividing skeletal muscle (SM) into sub-ranges of radiodensity can improve the prediction of short-term outcomes in the oncology setting. We aim to investigate whether the skeletal muscle mass, when divided into sub-ranges of low or high-radiodensity, improves the prediction of short-term survival in endometrial cancer (EC) patients when compared to average muscle attenuation and to the overall skeletal muscle radiodensity.

EC patients who had computed tomography (CT) images available within 30 days before treatment were enrolled in this retrospective cohort (n = 232). CT images at the third lumbar vertebra (L3) were used to assess overall skeletal muscle index (SMI). Then we divided SMI into sub-ranges of radiation attenuation: low-radiodensity skeletal muscle index (LRSMI) and high-radiodensity skeletal muscle index (HRSMI). The average muscle radiation attenuation was also assessed. Low SMI was defined when SMI was <38.9 cm²/m². One-year survival was evaluated by Kaplan-Meier method and Cox Regression.

Sarcopenia was found in 25.8% of the patients. Roughly 80% of the patients in the highest quartile of LRSMI were obese. All the skeletal muscle parameters were significantly associated with shorter 1-year survival, LRSMI presented a trend for significance in the adjusted model. When the SM parameters were additionally adjusted for low SMI, only HRSMI and LRSMI remained in the model as early-mortality predictors.

Classifying the skeletal muscle into sub-ranges of radiodensity have an additional value than using the average muscle attenuation of the overall skeletal muscle area and should be exploited in further studies.