Historical external beam radiation therapy (EBRT) for rectosigmoid cancer (RCa) predisposed patients to an increased risk of secondary bladder cancer (BCa). However, no contemporary radiotherapy studies are available. We addressed this knowledge gap.
Within the Surveillance, Epidemiology, and End Results database (2000-2020), we identified non-metastatic RCa patients who either underwent radiotherapy (EBRT+) or did not (EBRT-). Cumulative incidence plots and multivariable competing risk regression models (CRR) were fitted to address rates of BCa after RCa. In the subgroup of BCa patients, the same methodology addressed BCa-specific mortality (BCSM) according to EBRT exposure status.
Of the 188,658 non-metastatic RCa patients, 54,562 (29%) were EBRT+ vs. 134,096 (73%) who were EBRT-. In the cumulative incidence plots, the ten-year BCa rates were 0.7% in EBRT+ vs. 0.7% in EBRT- patients (p = 0.8). In the CRR, EBRT+ status was unrelated to BCa rates (multivariable HR: 1.1, p = 0.8). In the subgroup of 1416 patients with BCa after RCa, 443 (31%) were EBRT+ vs. 973 (69%) who were EBRT-. In the cumulative incidence plots, the ten-year BCSM rates were 10.6% in EBRT+ vs. 12.1% in EBRT- patients (p = 0.7). In the CRR, EBRT+ status was unrelated to subsequent BCSM rates (multivariable HR: 0.9, p = 0.9).
Although historical EBRT for RCa predisposed patients to higher BCa rates, contemporary EBRT for RCa is not associated with increased subsequent BCa risk. Moreover, in patients with BCa after RCa, exposure to EBRT does not affect BCSM.
Cancers. 2024 Jun 29*** epublish ***
Mario de Angelis, Carolin Siech, Francesco Di Bello, Natali Rodriguez Peñaranda, Jordan A Goyal, Zhe Tian, Nicola Longo, Felix K H Chun, Stefano Puliatti, Fred Saad, Shahrokh F Shariat, Mattia Longoni, Giorgio Gandaglia, Marco Moschini, Francesco Montorsi, Alberto Briganti, Pierre I Karakiewicz
Cancer Prognostics and Health Outcomes Unit, Division of Urology, University of Montréal Health Center, Montréal, QC H2X 3E4, Canada., Department of Neurosciences, Science of Reproduction and Odontostomatology, University of Naples Federico II, 80131 Naples, Italy., Department of Urology, University Hospital, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany., Department of Urology, Ospedale Policlinico e Nuovo Ospedale Civile S. Agostino Estense Modena, University of Modena and Reggio Emilia, 41121 Modena, Italy., Department of Urology, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria., Division of Experimental Oncology, Unit of Urology, URI, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.