Risk of radiation-induced secondary rectal and @entity150 following radiotherapy of XXXX .

@entity1 @entity263 @entity5 @entity3628 @entity150
BACKGROUND: An elevated risk of radiation-induced @entity5 ( @entity5 ) has been observed in @entity263 @entity1 after radiotherapy (RT), rising to as high as one in 70 @entity1 with more than 10 years follow-up. In this study we have estimated @entity5 risks following RT with both previous and contemporary techniques, including proton therapy, using risk models based on different dose-response relationships. MATERIAL AND METHODS: RT plans treating the prostate and seminal vesicles with either conformal radiotherapy (CRT), volumetric modulated arc therapy (VMAT) or intensity-modulated proton therapy (IMPT) were created for 10 @entity1 . The risks of radiation-induced @entity5 were estimated for the bladder and rectum using dose-response models reflecting varying degrees of cell sterilisation: a linear model, @entity3628 and a bell-shaped model also accounting for fractionated RT. RESULTS: The choice of risk models was found to rank the plans quite differently, with the CRT plans having the lowest @entity5 risk using the bell-shaped model, while resulting in the highest risk applying the linear model. Considering all dose-response scenarios, median relative risks of VMAT versus IMPT were 1.1-1.7 for the bladder and 0.9-1.8 for the rectum. Risks of radiation-induced @entity150 were lower from VMAT if exposed at 80 years versus IMPT if exposed at 50 years. CONCLUSIONS: The @entity5 risk estimations for the bladder and rectum revealed no clear relative relationship between the contemporary techniques and CRT, with divergent results depending on choice of model. However, the @entity5 risks for these organs when using IMPT were lower or comparable to VMAT. @entity5 risks could be assessed when considering referral of @entity263 @entity1 to proton therapy, taking also general @entity1 characteristics, such as age, into account.
