Background: Adjuvant radiotherapy (ART) has been recommended for squamous cell carcinoma(SCC) with a high risk of recurrence, particularly perineurally invasive disease. The utility of ART is unknown. This study compares reported outcomes of high-risk SCC treated with surgical monotherapy(SM) with those of surgery plus ART (S + ART).
Methods: The Medline database was searched for reports of high-risk SCC treated with SM or S + ART that reported outcomes of interest: local recurrence, regional or distant metastasis, or disease-specific death.
Results: There were no controlled trials. Of the 2,449 cases of high-risk SCC included, 91 were treated with S + ART. Tumor stage and surgical margin status before ART were generally unreported. In 74 cases of perineural invasion (PNI), outcomes were statistically similar between SM and S + ART. In 943 high risk SCC cases in which clear surgical margins were explicitly documented, risks of local recurrence,regional metastasis, distant metastasis, and disease-specific death were 5%, 5%, 1%, and 1%, respectively.
Conclusions: High cure rates are achieved in high-risk cutaneous SCC when clear surgical margins are obtained. Current data are insufficient to identify high-risk features in which ART may be beneficial. In cases of PNI, the extent of nerve involvement appears to affect outcomes, with involvement of larger nerves imparting a worse prognosis.