Key clinical point: Second primary malignancy (SPM) incidences are higher in patients with metastatic castration-resistant prostate cancer (CRPC).

Major finding: The incidence of SPM per 1,000 person-years was 81.8 (95% confidence interval, 78.8-85.0) in patients with metastatic prostate cancer with bone metastasis and 115.6 (95% confidence interval, 95.1-140.7) in those with metastatic CRPC. The median survival was 1.5 and 1.1 years, respectively.

Study details: Register-based study used data from the Prostate Cancer data Base Sweden (PCBaSe) and included 15,953 patients with prostate cancer and 693 patients with metastatic CRPC.

Disclosures: This study was supported by the Bayer AG. Several authors were Bayer employees.

Commentary

“Second primary malignancies (SPM) are a significantly understudied, but rather commonly encountered dilemma. Whether SPM are related to the first malignancy, previous treatments, co-morbidities, other genetic factors, or other clinical variables is neither well-studied, nor well-known. Mehtälä et al. evaluated the incidence and overall survival of patients with SPM in two cohorts: 1) men with bone metastatic prostate cancer (mPC) and 2) men with bone metastatic castrate-resistant prostate cancer (mCRPC). The incidence of SPM was higher in men with mCRPC while survival was slightly lower in the same cohort. Common SPM reported were lung, colorectal, bladder, and hematologic malignancies. As this was a descriptive study, the results confirm that SPM is an under-recognized issue in patients with prostate cancer that needs further study. “

Mark Klein, MD