Clinicopathologic Characteristics and Prognosis of Tongue Squamous Cell Carcinoma in Patients with and without a History of Radiation for Nasopharyngeal Carcinoma: A Matched Case-Control Study

PURPOSE Previous studies reported an association between an increased risk of tongue cancer and radiation treatment for nasopharyngeal carcinoma (NPC). This study compared the clinicopathologic characteristics and outcomes of tongue squamous cell carcinoma (TSCC) in patients with and without a history of radiotherapy for NPC. MATERIALS AND METHODS From 1965 to 2009, a total of 73 patients were diagnosed with TSCC with a history of radiotherapy for NPC. The patients were matched in a 1:3 ratio with patients with sporadic TSCC according to age, sex, and year of the TSCC diagnosis. The primary endpoint was the overall survival. RESULTS The median interval from NPC to TSCC was 82 months. The NPC survivors were more likely to be diagnosed with a more advanced T classification, less likely to have lymph node involvement, and more likely to have the tumor located in the dorsum of the tongue than sporadic TSCC. Regarding the histologic characteristics, the NPC survivors were more likely to have a weak lymphocytic host response, low tumor budding, and low risk of a worse pattern of invasion. The sporadic TSCC patients had a better overall survival (hazard ratio, 0.690; p=0.033) than the NPC survivors. In competing risks analysis, the cumulative incidence functions for the competing event (documented non-tongue cancer death) were significantly higher in the NPC survivors (Gray's test, p=0.001). CONCLUSION TSCC patients with a history of radiotherapy for NPC appear to have particular clinicopathologic features, a poorer survival, and are more likely to die from non-tongue cancer causes than those with sporadic TSCC.