Abstract
PURPOSE: The main goal of this study was to analyze the prognosis of secondary oral squamous cell carcinoma (SCC) with a comparison with sporadic oral SCC by a matched-pair design. MATERIALS AND METHODS: Records of patients with surgically treated primary oral SCC were reviewed, and a total of 83 patients with previous history of radiotherapy for nasopharyngeal carcinoma (NPC) were retrospectively enrolled. A matched-pair study was performed, each NPC survivor was matched with two sporadic oral SCC patients by age, sex, primary tumor site, adverse pathologic characteristics, disease stage, neck node status, and tumor stage. The overall survival (OS) and disease-specific survival (DSS) rates were calculated by the Kaplan-Meier method; independent prognostic factors were evaluated by the Cox proportional hazards method. RESULTS: Compared with sporadic oral SCC patients, NPC survivors were less likely to be smokers (p=0.004), perineural invasion and lymphovascular invasion were more common in NPC survivors (both p < 0.001). The 5-year OS and DSS rates in NPC survivors were 47% and 54%, respectively; the 5-year OS and DSS rates in sporadic oral SCC patients were 62% and 67%, respectively; the difference was significant (both p < 0.05). In survival analysis, disease stage remained to be independent prognostic factor for both the OS and DSS. CONCLUSION: NPC survivors had worse OS and DSS than sporadic oral SCC patients, NPC survivors were less likely to be smokers, but had higher opportunity of perineural invasion and lymphovascular invasion. Disease stage was the most important predictor for the survival in NPC survivors.