Purpose: To assess risk of developing a second benign brain tumor in a nationwide population of cancer survivors.
Methods: We evaluated the risk of developing second benign brain tumors among 2,038,074 1-year minimum cancer survivors compared to expected risk in the general population between 1973 and 2007 in nine population-based cancer registries in the NCI's surveillance, epidemiology, and end results program. Excess risk was estimated using standardized incidence ratios (SIRs) for all second benign brain tumors and specifically for second meningiomas and acoustic neuromas diagnosed during 2004-2008.
Results: 1,025 patients were diagnosed with a second primary benign brain tumor, of which second meningiomas composed the majority (n = 745). Statistically significant increases in risk of developing a second meningioma compared to the general population were observed following first cancers of the brain [SIR = 19.82; 95 % confidence interval (CI) 13.88-27.44], other central nervous system (CNS) (SIR = 9.54; CI 3.10-22.27), thyroid (SIR = 2.05; CI 1.47-2.79), prostate (SIR = 1.21; CI 1.02-1.43), and acute lymphocytic leukemia (ALL) (SIR = 42.4; CI 23.18-71.13). Statistically significant decreases in risk were observed following first cancers of the uterine corpus (SIR = 0.63; CI 0.42-0.91) and colon (SIR = 0.56; CI 0.37-0.82). Differences in risk between patients initially treated with radiotherapy versus non-irradiated patients were statistically significant for second meningioma after primary cancers of the brain (p Het < 0.001) and ALL (p Het = 0.02). No statistically significant increased risks were detected for second acoustic neuromas (n = 114) following any first primary tumor.
Conclusions: Risk of second benign brain tumors, particularly meningioma, is increased following first primary cancers of the brain/CNS, thyroid, prostate, and ALL. Radiation exposure likely contributes to these excess risks.