Abstract
BackgroundCurrent evidence on risk of prostate cancer following a diagnosis of male breast cancer is limited and guidance for screening in this potentially higher-risk population remainsunclear. Our objective was to quantify prostate cancer risk in men diagnosed with breast cancer.MethodsWe identified men diagnosed with first primary breast cancer between 1988 and 2012 using the Surveillance, Epidemiology and End Results Program registry databases. Men were followed for occurrence of a second primary prostate cancer and secondary outcomes of cancer-specific and overall survival. Stratified analyses were performed by age, breast cancer stage, race, and breast cancer hormone receptor status. Excess risk per 10,000 person-years and standardized incidence ratios (SIR) with 95% confidence intervals (95% CI) were calculated. We used multivaraible Cox proportional hazard models to estimate hazard ratios (HR) and 95% CI for characteristics associated with secondary prostate cancer and survival.ResultsFrom a cohort of 5753 men with breast cancer with median follow up of 4.3 years, we identified 250 cases of second primary prostate cancer. Overall, the incidence of second primary prostate cancer was modestly greater than expected (SIR = 1.12, 95% CI 0.93–1.33), although not statistically significant. Stratified analyses demonstrated associations for men ages 65–74 at the time of breast cancer diagnosis (SIR = 1.34, 95%CI 1.01–1.73), hormone receptor-positive breast cancer (SIR = 1.23, 95%CI 1.11–1.39) or AJCC stage I breast cancer (SIR = 1.36, 95%CI 1.04–1.75) and second primary prostate cancer diagnosis.ConclusionsThe incidence of prostate cancer in men with history of breast cancer is similar to the general population. Men with favorable characteristics of their breast cancer were more likely to develop prostate cancer, possibly due to a lower competing risk of breast cancer mortality.
Highlights
Current evidence on risk of prostate cancer following a diagnosis of male breast cancer is limited and guidance for screening in this potentially higher-risk population remainsunclear
BRCA2 mutations have been shown in one study, which did not select for family history, to have a prevalence of 14% in a male breast cancer population [8]
Second primary cancers were defined based on previously established SEER criteria [18] requiring a second primary malignancy subsequent to the index first primary male breast cancer to be located in a site with a different International Classification of Diseases for Oncology third edition (ICD-O-3) code and not documented as a metastasis in the clinical record
Summary
Current evidence on risk of prostate cancer following a diagnosis of male breast cancer is limited and guidance for screening in this potentially higher-risk population remainsunclear. Our objective was to quantify prostate cancer risk in men diagnosed with breast cancer. Known risk factors for these hormonally dependent cancers are not overlapping, with the exception of rare individuals harboring susceptibility alleles in the BRCA2 (and less commonly BRCA1) gene. Male breast cancer and prostate cancer have both been associated with germline mutations in the BRCA1/2 tumor suppressor genes [6, 7]. BRCA2 mutations have been shown in one study, which did not select for family history, to have a prevalence of 14% in a male breast cancer population [8]. In men under 65 years of age, carriers of mutated BRCA1 have a 1.8 fold increased risk of prostate cancer [9] and BRCA2 carriers an 8.6 fold
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