Citation: Urologic Oncology. 36(11):500.e11-500.e19, 2018 11..Journal: Urologic oncology.Published: ; 2018ISSN: 1078-1439.Full author list: Krasnow RE; Rodriguez D; Nagle RT; Mossanen M; Kibel AS; Chang SL.UI/PMID: 30249519.Subject(s): Adult | Age Factors | Aged | Humans | Incidence | Kaplan-Meier Estimate | Male | Middle Aged | *Neoplasms, Radiation-Induced/ep [Epidemiology] | Proportional Hazards Models | *Prostatic Neoplasms/rt [Radiotherapy] | Rectal Neoplasms/ep [Epidemiology] | *Rectal Neoplasms/et [Etiology] | SEER Program | Urinary Bladder Neoplasms/ep [Epidemiology] | *Urinary Bladder Neoplasms/et [Etiology]Institution(s): MedStar Washington Hospital CenterDepartment(s): UrologyActivity type: Journal Article.Medline article type(s): Journal ArticleOnline resources: Click here to access onlineDigital Object Identifier: https://dx.doi.org/10.1016/j.urolonc.2018.06.007 (Click here)Abbreviated citation: UROL. ONCOL.. 36(11):500.e11-500.e19, 2018 11.Abstract: PURPOSE: There is a known increased risk of second primary malignancy (SPM) in patients with prostate cancer (CaP) treated with radiotherapy (RT). It is unclear how age at diagnosis influences the risk of SPMs.Abstract: MATERIALS AND METHODS: Using the 1973 to 2013 Surveillance, Epidemiology, and End Results Program, we studied the impact of age on SPMs (defined as a bladder or rectal tumor) after localized CaP treatment with radical prostatectomy (RP) or RT. SPM risk was compared using inverse probability of treatment weighting (IPTW)-adjusted cumulative incidence function and competing-risk proportional hazard models. Overall survival (OS) in patients with SPM was compared using Kaplan Meier and Cox regression analyses.Abstract: RESULTS: A total of 579,608 patients met inclusion criteria, and 51.8% of the cohort was treated with RT. The 10- and 20-year cumulative incidences of competing risk (IPTW adjusted) of SPMs were 1.9% (95%CI = 1.8-1.9%) and 3.6% (95%CI = 3.4-3.7%) after RP vs. 2.7% (95%CI = 2.6-2.8%) and 5.4%(95%CI = 5.3-5.6%) after RT. IPTW-adjusted competing risk hazard ratio (HR) of SPM after RT compared to RP was increased in the entire cohort (HR 1.46; 95%CI = 1.39-1.53, P < 0.001) and was highest in the youngest patients: Age <55 HR = 1.83 (95% confidence interval [CI] = 1.49-2.24, P<0.001), Age 55 to 64 HR = 1.66 (95%CI = 1.54-1.79, P < 0.001), Age 65-74 HR = 1.41 (95%CI = 1.33-1.48, P < 0.001), Age >=75 HR = 1.14 (95%CI = 0.97-1.35, P = 0.112). At 10 years, SPM-specific mortality occurred in 28.9% of patients treated with RT, though OS with SPM was worse in the youngest patients: Age <55 HR = 1.88 (95%CI = 1.25-2.81, P= 0.002), Age 55-64 HR = 1.60 (95%CI = 1.42-1.81, P < 0.001), Age 65-74 HR = 1.40 (95%CI = 1.30-1.52, P < 0.001), Age >= 75 HR = 1.27 (95%CI = 1.06-1.53, P = 0.009). All of the age categories had similar median follow-up times.Abstract: CONCLUSION: At 10 years there is a 1.8% increased incidence of SPM after RT compared to RP, of which <30% of RT-treated patients with an SPM die as a result of a SPM. However, the risk of SPMs was greatest among younger men treated with RT for localized CaP, and this relationship could not be explained solely by follow-up time, latency time, or life expectancy. An improved understanding of those at the highest risk of SPMs may help tailor treatment and surveillance strategies.Abstract: Copyright (c) 2018 Elsevier Inc. All rights reserved.