Impact of Changes in Skeletal Muscle Mass Index on Prognosis During Alternating Chemoradiotherapy in Nasopharyngeal Carcinoma

Sarcopenia is common in patients with head and neck cancer and is suggested to be associated with decreased survival. This study aimed to investigate the relationship between changes in skeletal muscle mass during alternating chemoradiotherapy (CRT) and the prognosis of patients with nasopharyngeal carcinoma (NPC). This retrospective study included 64 patients with NPC who had undergone alternating CRT at our institution between 2005 and 2022. The skeletal muscle mass index (SMI) was measured using pre- and post-treatment computed tomography. SMI decreased in 58 patients (90.6%), with a mean change of -6.1%. Using a cutoff value of -6.0% for SMI change, 32 patients (50.0%) were categorized into the SMI loss group. The SMI loss group had a significantly lower mean overall survival (OS) than the SMI maintenance group (122.6 vs. 153.0 months; <i>p</i> = 0.021). Multivariate analysis identified SMI loss and prognostic nutritional index (PNI) as independent predictors of poor OS (<i>p</i> < 0.05). They were used to construct the nomogram of OS. In conclusion, SMI loss during alternating CRT was identified as a poor prognostic factor. These findings suggest that preserving skeletal muscle mass during alternating CRT may improve the prognosis and merits further investigation.