Analysis of overall survival in patients with second primary malignancies following with the first diagnosis of nonmetastatic prostate cancer: A study utilizing the Surveillance, Epidemiology, and End Results database.

[BACKGROUND] Survival in patients with prostate cancer (PCa) is now significantly prolonged. However, the incidence of secondary primary malignancies (SPMs) has increased during the treatment for PCa, which adversely affects patient survival. This study explored the factors influencing the overall survival (OS) of SPM in patients with nonmetastatic PCa and the impact of SPM with different histologic types on OS.

[MATERIALS AND METHODS] We evaluated the clinical data of patients diagnosed with PCa of T1N0M0 to T4N0M0 between 2010 and 2015 from the Surveillance, Epidemiology, and End Results database. The patients were divided into 2 groups: with or without SPM. The key risk factors affecting OS were analyzed using Cox regression analysis. To mitigate the influence of other confounding factors, we performed propensity score matching in a 1:1 ratio. The Kaplan-Meier method was used to assess the impact of SPM on OS across different histological types.

[RESULTS] In total, 208,984 patients with nonmetastatic PCa were enrolled, including 16,573 and 192, 411 patients in the SPM and non-SPM groups, respectively. Age ( < 0.05), chemotherapy ( = 0.010), presence of SPM ( < 0.05), Gleason score of the biopsy specimens ( < 0.05), and prostate-specific antigen levels ( < 0.05) were identified as independent risk factors for OS. Conversely, race ( < 0.05), radical prostatectomy ( < 0.05), and radiotherapy ( < 0.05) were independent protective factors of OS. The 5-year OS rate was worse in the SPM group than in the non-SPM group (72.9% vs. 91.2%, < 0.05). Patients with SPM of the pulmonary and bronchial types have the worst long-term prognosis, whereas those with SPM of cutaneous melanoma have the best prognosis.

[CONCLUSIONS] During the management of patients with PCa, we must extend our attention beyond potential PCa recurrence and metastasis to the possibility of SPM, which compromises patient survival.