Dose-response relations between radiotherapy dose and relative risk (RR) of second neoplasms. (A) Subsequent neoplasms of the CNS were classified as meningioma (yellow squares) or glioma (blue squares). Fitted lines were calculated by Poisson regression and indicated positive relations between radiotherapy dose and higher RR of both tumors.(B) The RR of subsequent thyroid cancer seemed to be associated with radiotherapy doses less than 29 Gy. OR, odds ratio.