Clinicopathologic characteristics of second primary squamous cell carcinoma in patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy.

To compare the clinicopathologic characteristics of second primary squamous cell carcinoma (SPSCC) in patients with nasopharyngeal carcinoma (NPC) after intensity-modulated radiotherapy (IMRT) with that after radiotherapy (RT). From 49,021 patients with NPC who treated by definitive RT, we were able to identify 15 male patients with SPSCC after IMRT, and 23 male patients with SPSCC after RT. We examined the difference between groups. In IMRT group, 50.33% developed SPSCC within 3 years, whereas 56.52% developed SPSCC after more than 10 years in RT group. Receiving IMRT was related positively to an increased risk of SPSCC (HR = 4.25; P < 0.001). There was no significant correlation between receiving IMRT and the survival of SPSCC (P = 0.051). Receiving IMRT was related positively to an increased risk of SPSCC, and the latency was much shorter. A follow-up protocol, especially in the first three years, should be designed for NPC patients with IMRT.