IGSF3 tissue expression in squamous cell carcinoma of the oropharynx: a novel tool for prognosis assessment in HPV-related and HPV-unrelated disease.

Biomarkers are not broadly used in the management of head and neck cancers (HNCs). Biomarkers have been beneficial in the management of other cancers, however, not in HNCs. Therefore, we observed the immunopositivity of a novel biomarker called immunoglobulin superfamily member 3 (IGSF3) in tumor tissues in HPV-related and HPV-unrelated OPSCC. Two patient cohorts (C1 and C2) from separate time periods were available for this study (total N = 282). Both consisted of OPSCC patients treated at the Helsinki University Hospital (HUS, Helsinki, Finland) during 2000-2016. For HPV determination, HPV mRNA in situ hybridization was used. Immunohistochemistry was used to assess IGSF3 immunopositivity in cancer tissues. Overall survival (OS) was used as endpoint in the statistical analysis. In C1, stronger immunopositivity of IGSF3 in tumor-infiltrating lymphocytes (TILs) correlated with favorable OS (p = 0.005). Stronger IGSF3 immunopositivity in tumor cells (TCs) was associated with HPV negativity (p = 0.017). Stronger IGSF3 immunopositivity in TILs correlated with HPV positivity (p < 0.001). Elevated IGSF3 immunopositivity in TILs associates with HPV-related tumors and may signify favorable prognosis. The immunopositivity of IGSF3 differs between HPV-related and HPV-unrelated OPSCC.