Takahiro Hongo

The prevalence and prognostic value of human papillomavirus (HPV) infection and epidermal growth factor receptor (EGFR) alteration in sinonasal squamous cell carcinoma (SNSCC) are not known. The reliability of p16 overexpression as a surrogate for HPV infection in SNSCC is also unclear. We investigated the prognostic and diagnostic significances of HPV infection, EGFR alteration, and p16 expression in SNSCC. We analyzed high-risk HPV infection by HPV-RNA in situ hybridization and EGFR gene copy number gain (CNG) by chromogenic in situ hybridization and by determining the protein expressions of p16, Rb, and EGFR by immunohistochemistry in 101 SNSCC cases. HPV infection (n=9, 8.9%) and p16 overexpression (n=15, 14.9%) were associated with better overall survival (P=0.0042 and 0.005, respectively). The HPV cases were located predominantly at the nasal cavity with nonkeratinizing histology and partial loss of Rb. Notably, 40% (6/15) of p16 SNSCCs were HPV. Two of these cases showed complete loss of Rb expression by immunohistochemistry, suggesting a reason for the above discrepancy. EGFR CNG, detected in 30.5% of the SNSCCs, was correlated with EGFR protein overexpression (P=0.0001). HPV infection and EGFR CNG were mutually exclusive. The HPV/EGFR CNG group had significantly better overall survival than the HPV/EGFR CNG and HPV/EGFR CNG groups (P=0.0471 and 0.0343, respectively). Our results suggest that HPV infection is a favorable prognostic marker in SNSCC, but p16 is not a perfect surrogate marker; the Rb expression pattern may improve the diagnostic accuracy. The molecular subclassification of SNSCCs based on HPV infection and EGFR copy number status might provide important information for therapeutic strategies.

Sinonasal squamous cell carcinoma (SNSCC) is sometimes associated with high-risk human papillomavirus (HR-HPV) infection and inverted sinonasal papilloma or oncocytic sinonasal papilloma. Frequent mutations of EGFR and KRAS are reported in inverted sinonasal papilloma-related sinonasal squamous cell carcinoma (ISP-SCC) and oncocytic sinonasal papilloma-related SNSCC, respectively. Here, we attempted to determine the prevalence and the prognostic significances of these alterations in SNSCC. We retrospectively collected 146 SNSCCs, including 14 ISP-SCCs, and comprehensively analyzed the HR-HPV infection by human papillomavirus (HPV)-RNA in situ hybridization, EGFR gene copy number gain (CNG) by chromogenic in situ hybridization, and gene mutations in EGFR and KRAS by Sanger sequencing. HR-HPV was detected in 11 cases (7.5%), whereas all 14 ISP-SCCs were negative. EGFR mutations were present in 21 (14.7%) of 143 SNSCCs, including 13/14 (92.9%) ISP-SCCs and 8/129 (6.2%) non-ISP-SCCs (P<0.0001). The majority of EGFR mutations were exon 20 insertions, with the remainder composed of deletions and single-nucleotide substitutions in exons 19 and 20. All of 142 SNSCCs harbored no KRAS mutation. EGFR CNG was detected in 41 (28.1%) of 146 SNSCCs; all of them were HPV negative and 3 had EGFR mutations. Collectively, EGFR mutation, EGFR CNG, and HR-HPV were essentially mutually exclusive, and each subgroup had distinct clinicopathologic features. The HPV-negative/EGFR-mutant group, the HPV-negative/EGFR CNG-positive group, and the triple-negative group had significantly worse prognoses than the HPV-positive group (P=0.0265, 0.0264, and 0.0394, respectively). In conclusion, EGFR mutation may play a pathogenetically important role in some populations of SNSCCs, especially ISP-SCCs. The molecular subclassification of SNSCCs may contribute to prognostic prediction and molecular-targeted precision medicine.

OBJECTIVES/HYPOTHESIS: The extreme rarity of temporal bone squamous cell carcinoma (TB-SCC) has delayed the accumulation of high-quality clinical evidence. For the purposes of retrospective meta-analysis in the future, a large dataset with information from various institutions would be ideal. Our objective here was to retrospectively review cases of TB-SCC encountered at a single tertiary referral center and explore survival outcomes and prognostic factors. STUDY DESIGN: Retrospective chart review. METHODS: The medical records of all TB-SCC cases were retrospectively reviewed. The resulting dataset contained 71 cases of primary cancer eligible for initial definitive (curative) treatment. RESULTS: T4 status was associated with lower disease-specific 5-year survival than T1 to T3 staging (T1: 100%, T2: 92%, T3: 86%, T4: 51%). Survival was significantly higher in operable than in inoperable cases, even when restricted to advanced (T3/T4) cancers. The tumor extension to the middle ear cavity was observed in 13/17 of T3 cases, but it was not associated with poor survival. In addition, among operable cases, negative surgical margins were associated with significantly higher survival than positive margins. CONCLUSIONS: Definitive treatments can offer disease-specific 5-year survival of over 85% in T1 to T3 cases of TB-SCC. The tumor extension to the middle ear cavity is not associated with poor survival. T4 status, inoperability, nodal invasion, and positive surgical margin are identified as a predictor of poor prognosis. Still, the matter of how to deal with unresectable tumors remains an outstanding issue in the treatment of TB-SCC. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E583-E589, 2021.