Radiation therapy has been associated as a risk factor for the development of bladder cancer. It remains unknown if radiation-induced bladder tumors have clinically significant differences as these tumors have not been well characterized. Previous studies are limited to bladder cancers that develop after radiation for prostate cancer. Using a large-scale population analysis, we evaluate bladder cancers in any patient having undergone radiation therapy and demonstrate an association between prior radiation and bladder cancer survival.
Patients diagnosed with bladder cancer as a second malignancy between 1975-2016 were identified in the Surveillance, Epidemiology, and End Results (SEER) 9 Program. Demographic and clinical factors as well as radiation history for the primary tumor were obtained. Patients undergoing radiation for whom the bladder would likely be outside the radiated field were excluded. The final study population included 15,034 patients. Kaplan-Meier survival curves and multivariate Cox regression models with non-proportional hazards were used to assess the association between previous radiation and bladder cancer survival. A sub-analysis was performed for patients with available T-stage data to evaluate stage-specific survival (N=9,642).
Approximately 39.7% of patients received radiation for their initial malignancy. Survival time ranged from 0 to 41.3 years after bladder cancer diagnosis (median 3.42 years). Overall, patients with prior radiation had a significantly increased risk of five-year all-cause and bladder cancer-specific mortality, although this effect was not sustained (Figure 1). For non-muscle invasive bladder cancer, prior radiation was associated with elevated all-cause (CIS-HR 1.53, CI 1.21-1.92; Ta-HR 1.51, CI 1.35-1.68; T1-HR 1.09, CI 0.95-1.24) and bladder cancer-specific (CIS-HR 2.16, CI 1.34-3.47; Ta-HR 1.35, CI 1.06-1.73; T1-HR 1.26, CI 0.96-1.67) mortality at five years. For patients with carcinoma in situ, there was also a suggestion of increased risk at 10 years (HR 1.48, CI 0.92-2.38). For muscle invasive disease, there was a trend towards increased five-year bladder cancer-specific mortality.
Prior radiation therapy may confer a survival disadvantage for patients diagnosed with bladder cancer as a second malignancy.
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EFFECT OF PRIOR RADIATION ON SURVIVAL IN BLADDER CANCER: A POPULATION ANALYSIS
Bladder Cancer > Other
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Presented By: Syed M. Alam, MD
Syed M. Alam
Lynn Chollet-Hinton, PhD
Jeffrey Thompson, PhD
Jeffrey M. Holzbeierlein, MD