Radiation-Induced Schwannomas and Neurofibromas: A Systematic Review

OBJECTIVE: Radiation-induced benign peripheral nerve sheath tumors are uncommon late complications of irradiation. We conducted the largest systematic review of individual patient data. METHODS: We performed a systematic search of PubMed databases and compiled a comprehensive literature review. Kaplan-Meier analysis was used to investigate survival, and statistical significance was assessedwith a log-rank test. RESULTS: We analyzed 40 cases of radiation-induced benign peripheral nerve sheath tumors. The histologic distributions were 28 schwannomas,11 neurofibromas, and 1 ganglioneuroma. The average age of radiation exposure for development of primary lesions was 14.9 +/- 15.5 years, and the latency period between radiotherapy to the onset of secondary tumors was 24.5 +/- 12.7 years. The average irradiation dose delivered was 26.3 +/- 20.3 Gy. The median overall survival for all cases was not reached (95% confidence interval, 22-not reached) months, with 10-year survival rates of 65.2%. Surgical negative margin was a positive prognostic factor for radiation-induced benign peripheral nerve sheath tumors. CONCLUSIONS: The risk of incidence of secondary benign peripheral nerve sheath tumors in patients treated with radiotherapy should be considered in long-term follow-up periods. At present, complete surgical resection is the main stay for the treatment of radiation-induced benign peripheral nerve sheath tumors.