The aim of this study was to investigate the impacts of radiation therapy (RT) on the occurrence risk of secondary bladder cancer (SBC) and on the patients' survival outcome after being diagnosed with gynecological cancer (EC). The data was obtained from the SEER database between 1973 and 2015. Chi-squared test was used to compare the clinicopathological characteristics among the different groups. Fine and Gray's competing risk model was used to assess the cumulative incidence and occurrence risk of SBC in GC survivors. Kaplan-Meier method was utilized for survival analysis. A total of 123,476 GC patients were included, among which 31,847 (25.8%) patients received RT while 91629 (74.2%) patients did not. The cumulative incidence of SBC was 1.59% or 0.73% among patients who had received prior GC specific RT or not, respectively. All EBRT (standardized incidence ratio (SIR) =2.49, 95% CI [2.17-2.86]), brachytherapy (SIR =1.96, 95% CI [1.60-2.38]), and combinational RT modality groups (SIR =2.73, 95% CI [2.24-3.28]) had dramatically higher SBC incidence as compared to the US general population. Receiving EBRT (HR = 2.83, 95% CI [2.34-3.43]), brachytherapy (HR = 2.17, 95% CI [1.67-2.82]), and combinational RT modality (HR = 2.97, 95% CI [2.34-3.77]) were independent risk factors for SBC development. Survival detriment was observed in SBC patients who received RT after GC diagnosis, as compared to those who did not receive RT. In conclusion, patients who underwent RT after GC had an increased risk of developing bladder as a secondary primary cancer. A long-term surveillance for SBC occurrence is necessary for GC patients who have received prior RT.

中文翻译：

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妇科癌症术后放疗后继发性膀胱癌的风险和预后。

本研究的目的是调查放射治疗（RT）对继发性膀胱癌（SBC）发生风险以及诊断为妇科癌症（EC）后患者生存结果的影响。数据取自SEER数据库1973年至2015年，采用卡方检验比较不同组间的临床病理特征。Fine 和 Gray 的竞争风险模型用于评估 GC 幸存者中 SBC 的累积发生率和发生风险。采用Kaplan-Meier法进行生存分析。总共纳入了 123,476 例 GC 患者，其中 31,847 例（25.8%）患者接受了放疗，而 91629 例（74.2%）患者没有接受放疗。在既往接受过 GC 特异性放疗或未接受过 GC 特异性放疗的患者中，SBC 的累积发生率分别为 1.59% 或 0.73%。所有 EBRT（标准化发生率 (SIR) = 2.49，95% CI [2.17-2.86]）、近距离放射治疗（SIR = 1.96，95% CI [1.60-2.38]）和组合 RT 治疗组（SIR = 2.73，95%）与美国普通人群相比，CI [2.24-3.28]）的 SBC 发生率显着升高。接受 EBRT（HR = 2.83，95% CI [2.34-3.43]）、近距离放射治疗（HR = 2.17，95% CI [1.67-2.82]）和组合 RT 方式（HR = 2.97，95% CI [2.34-3.77]） ）是 SBC 发展的独立风险因素。与未接受放疗的患者相比，在 GC 诊断后接受放疗的 SBC 患者中观察到生存受到损害。总之，GC 后接受 RT 的患者发生膀胱继发原发癌的风险增加。对于既往接受过 RT 的 GC 患者，有必要长期监测 SBC 的发生。