The prevalence and prognostic significance of high-risk human papillomavirus (HR-HPV) have been well-established in oropharyngeal squamous cell carcinoma (OPSCC), but not in hypopharyngeal squamous cell carcinoma (HPSCC) or laryngeal squamous cell carcinoma (LSCC). Moreover, HR-HPV infection in squamous cell carcinoma with multisite involvement has not been examined. To clarify these issues, we retrospectively collected 480 invasive tumors from 467 patients with HPSCC, LSCC, or OPSCC, and comprehensively analyzed the detailed tumor localization, transcriptionally active HR-HPV infection by messenger RNA in situ hybridization, and immunohistochemical staining for p16 and Rb. HR-HPV infection was observed in 115/480 tumors (24%). Human papillomavirus (HPV)-positive cases were closely related with p16 positivity and the partial loss pattern of Rb. HR-HPV was detected in 104 of 161 tumors (64.6%) in the pure OPSCC group and only 1 of 253 tumors (0.4%) in the pure HP/LSCC group; the positive case occurred in the vocal cords. In the multisite-involving combined-type squamous cell carcinoma group, HPV infection was observed in 10/40 (25%) cases, and the 10 HPV-positive cases had OPSCC extending to the larynx or hypopharynx. Among high T-stage (T3/T4) cases of pure OPSCC, HPV-positive cases showed a better prognosis ( P =0.0144), whereas the HPV-positive combined OPSCC group did not show a better prognosis ( P =0.9428), as compared with HPV-negative counterpart. The results suggest that HR-HPV infection in pure HPSCC and LSCC may be extremely rare. HR-HPV infection seems to be present in a substantial proportion of patients with combined OPSCC and HPSCC/LSCC, but it may not improve prognosis at such advanced disease stages. Confirmation of these points awaits future studies with larger cohorts.
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