OBJECTIVETo investigate the clinical characteristics and prognosis of second primary tumor of tongue (SPTr) after nasopharyngeal carcinoma (NPCR) treated with radiotherapy.

METHODSClinical data of 53 patients with SP7T after NPCR (group A) and 252 patients with primary tongue carcinoma (group B) were analyzed retrospectively with regard to clinical characteristics and survival rate (Kaplan-Meier); and multivariate analysis was performed using Cox proportional hazards model.

RESULTSThere was no significant difference between group A and group B ( P > 0. 05) in the presenting age, sex, tumor size, cTNM stage, tumor differentiation and the rate of distant metastasis. The overall 5-year survival rates were 41.6% in group A and 56.3% in group B (chi2 = 4.40, P = 0.0359) with a statistically significant difference between two groups. The differences of tumor location (chi2 = 61.18, P = 0.000) and rate of clinical (cN+, chi2 = 6.846, P = 0.009) or pathological lymph node metastasis (pN+, X2 = 3.993, P = 0.046) were also statistically significant between group A and group B, respectively. Multivariate analysis showed that age at presence, cTNM stage and with or without neck lymph node dissection were independent risk factors affecting survival.

CONCLUSIONSecond primary tongue carcinoma after radiotherapy for nasopharyngeal carcinoma is likely to occur on the dorsal aspect of the tongue with worse prognosis but with a lower rate of lymph node metastasis than that of primary tongue carcinoma. However, radiotherapy history is not an independent influencing factor on prognosis. Surgical resection or combined modality therapy may give a better prognosis.