Primary and Post-irradiation Spindle Cell Carcinoma of the Head and Neck: Clinical Characteristics and Molecular Signatures

Spindle cell carcinoma of the head and neck (HNSpCC) is a rare variant of squamous cell carcinoma (SCC). The clinicopathologic feature and prognostic factors of such tumors are unclear. In this study, we reviewed 71 patients with HNSpCC and found that HNSpCC had a higher local recurrence and distant metastasis rate than conventional HNSCC. In addition, we also found that a substantial proportion of SpCC arose from a previously irradiated field (post-RT SpCC) and presented with extremely aggressive behaviors. Whole exome sequencing revealed that post-RT SpCC had similar mutational landscapes to their prior SCC, but gained additional genetic traits such as hypoxia and cell-ECM interaction that were favorable for survival in an irradiated microenvironment. Distinct genetic landscapes in primary and post-RT SpCC were also found.