Pre-NCRT low SMA was a significant prognostic factor for both disease-free survival (DFS) (HR 2.611, 95% CI 1.129–6.040, p = 0.025) and cancer-specific survival (CSS) (HR 3.124, 95% CI 1.030–9.472, p = 0.044) in the Cox regression multivariate analysis. This evidence concerns the gene SMN1 and cancer.