Radiation-Induced Cranial Nerve Palsy: A Cross-Sectional Study of Nasopharyngeal Cancer Patients After Definitive Radiotherapy

Purpose: To address the characteristics and the causative factors of radiation-induced cranial nerve palsy (CNP) in nasopharyngeal carcinoma (NPC) patients with an extensive period of followed-up. Patients and Methods: A total of 317 consecutive and nonselected patients treated with definitive external-beam radiotherapy between November 1962 and February 1995 participated in this study. The median doses to the nasopharynx and upper neck were 71 Gy (range, 55–86 Gy) and 61 Gy (range, 34–72 Gy), respectively. Conventional fractionation was used in 287 patients (90.5%). Forty-five patients (14.2%) received chemotherapy. Results: The median follow-up was 11.4 years (range, 5.1–38.0 years). Ninety-eight patients (30.9%) developed CNP, with a median latent period of 7.6 years (range, 0.3–34 years). Patients had a higher rate of CNP (81 cases, 25.5%) in lower-group cranial nerves compared with upper group (44 cases, 13.9%) (χ2 = 34.444, p < 0.001). Fifty-nine cases experienced CNP in more than one cranial nerve. Twenty-two of 27 cases (68.8%) of intragroup CNP and 11 of 32 cases (40.7%) of intergroup CNP occurred synchronously (χ2 = 4.661, p = 0.031). The cumulative incidences of CNP were 10.4%, 22.4%, 35.5%, and 44.5% at 5, 10, 15, and 20 years, respectively. Multivariate analyses revealed that CNP at diagnosis, chemotherapy, total radiation dose to the nasopharynx, and upper neck fibrosis were independent risk factors for developing radiation-induced CNP. Conclusion: Radiation-induced fibrosis may play an important role in radiation-induced CNP. The incidence of CNP after definitive radiotherapy for NPC remains high after long-term follow-up and is dose and fractionation dependent. [ABSTRACT FROM AUTHOR]