BIRC5 and squamous cell carcinoma: In contrast, higher risk of PFS shortening was independently associated with the histopathological diagnosis of squamous cell carcinoma (HR = 2.85, 95% CI: 1.24–6.54, p = 0.0138) and the GG genotype of the BIRC5 gene (HR = 1.92, 95% CI: 1.15–3.24, p = 0.0136).