Second primary squamous cell carcinoma in patients with nasopharyngeal carcinoma after radiotherapy predictors and prognostic factors.

Background: We investigated risk and prognostic factors for second primary squamous cell carcinoma (SCC) in patients with nasopharyngeal carcinoma (NPC) after radiotherapy (RT). Methods: A total of 49 021 patients with NPC were treated at Sun Yat-Sen Cancer Center between January 1970 and December 2009. The incidence and management of second primary SCCs were analyzed. Results: A total of 142 patients (0.29%) developed second primary SCC, with 78.2% in the upper aerodigestive tract. Older age, smoking, and chemotherapy were associated with an increased rate of second primary SCC. The 3, 5, and 10-year overall survival (OS) rates for second primary SCC were 47.18%, 31.69%, and 11.97%, respectively. Advanced age, family history of cancer, and treatment modality were independent prognostic factors for survival. Conclusion: Second primary tumors rarely develop in patients with NPC treated with RT, but when this occurs, second primary SCC comprises a majority of these. Intensity-modulated RT may shorten the latency to second primary SCC. Surgery as the first-line treatment may improve survival and prognosis.