We aim at describing the incidence, potential predisposing factors, and progression of major radiotherapy-related neurologic complications (RRNC) in nasopharyngeal carcinoma (NPC)-endemic regions, especially southern China.
We performed a multicenter longitudinal retrospective study with clinical follow-ups in 22,302 patients with post-radiotherapy NPC between January 2003 and June 2017 covering three major residential areas. Epidemiology, potential predisposing/protective factors, clinicopathologic progression, and survival conditions of each RRNC were separately recorded and analyzed on the basis of their related clinical, radiologic, and laboratory parameters.
949 new cases of RRNCs occurred among the 22,302 patients with post-radiotherapy NPC during 101,714 person years’ follow-up, which is equal to an incidence density rate of 9.3 new cases per 1000 person year. Radiation-induced cranial nerve palsy showed the highest incidence (2.68%, 597/22,302) with the earliest onset (median latency, 4.45 years) as well. Patients benefited from intensity-modulated radiotherapy (IMRT) over conventional radiotherapy (CRT) in both overall survival (median survival 13.2 years for IMRT vs. 8.3 years for CRT) and RRNC-free survival (except for epilepsy and cranial nerve palsy). Causes of death varied substantially between patients with or without RRNCs.
Our study indicates a non-negligible incidence of RRNC spectrum in southern China in the past ten years. IMRT is one of the most significant protectors against development and progression of RRNCs.
Our findings support the hypothesis that patients with NPC with preexisting predispositions would receive long-term benefits from IMRT and other dose-related modulations (like hyperfractionation and dose conformation).