Sinonasal squamous cell carcinoma and the prognostic implications of its histologic variants: A population-based study

Background: Variants of squamous cell carcinoma (SCC) make up 15% of all cases of SCC of the upper aerodigestive tract. There are 5 main histologic variants of SCC in the head and neck region: verrucous (VSCC), papillary (PSCC), spindle cell (sarcomatoid) (SCSC), basaloid (BSCC), and adenosquamous (ASC). Conventional sinonasal SCC has been studied extensively, but far less is known about its major variants. Methods: The Surveillance, Epidemiology, and End Results (SEER) database was used to extract frequency and survival data from 1973 to 2009. A total of 4382 cases of conventional sinonasal SCC and 328 cases of its major variants were found. Statistical comparisons of data for sinonasal SCC and its variants were carried out with respect to varying demographic and disease specific parameters, such as gender, race, age at diagnosis, and specific anatomic site affected. Results: Sinonasal BSCC was diagnosed at a significantly lower mean age than sinonasal SCC. Sinonasal SCSC significantly affected the maxillary sinus more commonly than SCC. In the setting of advanced stage disease, sinonasal VSCC, PSCC, and BSCC appear to be associated with a better prognosis than conventional sinonasal SCC, whereas the impact of histologic subtype on prognosis in early stage disease appears to be more limited. Survival for SCSC and ASC, both regarded as more lethal variants, was statistically similar to conventional SCC. Conclusion: Our study supports the practice of distinguishing between conventional sinonasal SCC and its major histologic variants, because histologic subtype appears to carry important prognostic implications.