Heterogeneity of TERT promoter mutations status in squamous cell carcinomas of different anatomical sites

Squamous cell carcinoma (SCC) can arise from different anatomical sites including the skin, head and neck, lung, esophagus, genital area, and so on. Despite the same histopathologic features and immunohistochemistry profile, the SCCs of different body sites can show tremendous differences in their presenting symptoms, risk factor associations, natural history, prognosis, and response to treatment. This may reflect the fact that SCCs are heterogenous and likely have unique molecular characteristics at different anatomical sites. Recurrent somatic mutations in the TERT promoter region were first reported in human melanomas. Subsequently, other tumors including cutaneous SCC were found to demonstrate high frequencies of the same mutations. However, the incidences of TERT promoter mutation in noncutaneous SCCs have not been systemically studied. We investigated the TERT promoter mutation status among SCCs from different sites. We collected 84 cases of SCC from the skin (27), head and neck (12), lung (25), and cervix (10), as well as 10 cases of urothelial carcinoma with squamous differentiation (UC-SqD). We found that the frequencies of TERT promoter mutation among SCC of different sits are quite heterogenous: ~70% in skin SCC and UC-SqD, 16.67% in head and neck SCC, and 0% in lung and cervix SCC. These results may support the hypothesis of different carcinogenesis mechanisms of SCC in different sites. It also indicates that TERT promoter mutation could be a biomarker for distinguishing skin SCC or UC-SqD vs pulmonary SCC.