Is skeletal muscle loss associated with chemoradiotherapy toxicity in nasopharyngeal carcinoma patients? A prospective study.

Background: Our study explored to investigate whether skeletal muscle loss before concurrent chemoradiotherapy (CCRT) can predict treatment-related toxicity in this population.

Methods: Computed tomography (CT) scan of the third lumbar were used to assess and calculate the SMA (skeletal muscle area), SMI (skeletal muscle index), SMD (skeletal muscle density), SMG (skeletal muscle gauge) and estimate LBM (lean body mass). Handgrip strength (HGS) and daily walk speed were evaluated. Predictive factors linked to toxicity were assessed by logistic regression models and adjusted odds ratios (OR) of treatment toxicity were reported.

Results: A total of 82 patients were evaluated (67.1% males, 45.7 ± 10.7 years). Skeletal muscle loss was not associated with severe radiotherapy toxicity. In males, sarcopenia increases the risk of dose-limiting toxicity (DLT) (OR: 4.00, 95% CI = 1.20-13.36, p = 0.024). DLT is associated with reduced SMA (OR: 0.97, 95% CI = 0.94-1.00, p = 0.041), SMI (OR: 0.91, 95% CI = 0.84-0.99, p = 0.042) and LBM (OR: 0.90, 95% CI = 0.81-0.99, p = 0.041). Reduced HGS was significantly associated with grade 3-4 leukopenia (OR: 0.92, 95% CI = 0.86-0.98, p = 0.007), and was associated with any grade 3-4 toxicity (OR: 0.94, 95% CI = 0.89-0.99, p = 0.013). There is a strong correlation between LBM and HGS (Pearson's r = 0.71, p < 0.001).

Conclusions: Skeletal muscle loss was not associated with severe radiation oral mucositis and dermatitis but associated with any grade 3-4 toxicity and severe gastrointestinal reactions in NPC patients. In males, sarcopenia before treatment is predictive of DLT. Increased HGS is independently associated with a reduced risk of hematological toxicity.