CBCT-based longitudinal assessment of muscle loss in oropharyngeal cancer patients undergoing radiochemotherapy

F. Fiorica, M. Coeli, G. Condarelli, S. Tomasi, U. Tebano, G. Mon, J. Giuliani, M. Gabbani, T. Sava, S. De Rossi, G. Tonoli, A. Casirati, R. Caccialanza, P. Pedrazzoli

Radiation Oncology and Nuclear Medicine Unit, AULSS 9 Scaligera, Verona, Italy. francesco.fiorica@aulss9.veneto.it

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• Oncology

OBJECTIVE: Oropharyngeal cancer and its treatment often lead to sarcopenia, which is linked to increased toxicity, reduced response to therapy, and worse survival. Traditional weight-based metrics may fail to detect this muscle loss. This study investigates the feasibility of using cone-beam computed tomography (CBCT) to monitor sarcopenia longitudinally in patients undergoing radiochemotherapy.

MATERIALS AND METHODS: A retrospective analysis was conducted on 15 patients with locally advanced, inoperable oropharyngeal cancer who maintained stable body weight during treatment. All patients received intensity-modulated radiotherapy (IMRT) or volumetric arc therapy (VMAT), with daily cone-beam computed tomography (CBCT) for image guidance. Skeletal muscle area and density at the C3 vertebral level were measured weekly. A calibration phantom corrected CBCT Hounsfield Unit (HU) values. Longitudinal changes were assessed using linear mixed-effects models (LMMs), and correlations between skeletal muscle index (SMI) and body mass index (BMI) were evaluate.

RESULTS: A significant weekly decline in SMI (p = 0.037) was observed, particularly after week 3, despite stable BMI. The muscle area decreased progressively while the HU values remained stable. A moderate inverse correlation was found between SMI and BMI (r = –0.39, p < 0.001), indicating that BMI is an inadequate measure for reflecting muscle loss.

CONCLUSIONS: CBCT allows non-invasive, real-time monitoring of sarcopenia during treatment. Integrating CBCT-based body composition analysis into clinical practice could enable earlier detection and intervention, potentially improving treatment tolerance and outcomes. Larger studies and improved segmentation techniques are needed to validate and optimize this approach.

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