Might men diagnosed with metastatic prostate cancer benefit from definitive treatment of the primary tumor? A SEER-based study

Abstract

Background: Few data exist regarding the impact on survival of definitive treatment of the prostate in men diagnosed with metastatic prostate cancer (mPCa).

Objective: To evaluate the survival of men diagnosed with mPCa based on definitive treatment of the prostate.

Design, setting, and participants: Men with documented stage IV (M1a-c) PCa at diagnosis identified using Surveillance Epidemiology and End Results (SEER) (2004-2010) and divided based on definitive treatment of the prostate (radical prostatectomy [RP] or brachytherapy [BT]) or no surgery or radiation therapy (NSR).

Outcome measurements and statistical analysis: Kaplan-Meier methods were used to calculate overall survival (OS). Multivariable competing risks regression analysis was used to calculate disease-specific survival (DSS) probability and identify factors associated with cause-specific mortality (CSM).

Results and limitations: A total of 8185 patients were identified: NSR (n=7811), RP (n=245), and BT (n=129). The 5-yr OS and predicted DSS were each significantly higher in patients undergoing RP (67.4% and 75.8%, respectively) or BT (52.6 and 61.3%, respectively) compared with NSR patients (22.5% and 48.7%, respectively) (p<0.001). Undergoing RP or BT was each independently associated with decreased CSM (p<0.01). Similar results were noted regardless of the American Joint Committee on Cancer (AJCC) M stage. Factors associated with increased CSM in patients undergoing local therapy included AJCC T4 stage, high-grade disease, prostate-specific antigen ≥20 ng/ml, age ≥70 yr, and pelvic lymphadenopathy (p<0.05). The major limitation of this study was the lack of variables from SEER known to influence survival of patients with mPCa, including treatment with systemic therapy.

Conclusions: Definitive treatment of the prostate in men diagnosed with mPCa suggests a survival benefit in this large population-based study. These results should serve as a foundation for future prospective trials.

Patient summary: We used a large population-based cancer database to examine survival in men diagnosed with metastatic prostate cancer (mPCa) undergoing definitive therapy for the prostate. Local therapy (LT) appeared to confer a survival benefit. Therefore, we conclude that prospective trials are needed to further evaluate the role of LT in mPCa.

Keywords: Brachytherapy; Metastatic prostate cancer; Outcomes assessment; Radical prostatectomy.