Post-Metastasis Survival of Patients with High-Risk Localized and Locally Advanced Prostate Cancer Undergoing Primary Treatment in the United States: A Retrospective Study.

Background: Patients with high-risk localized and locally advanced prostate cancer (HR-LPC/LAPC) have increased risk of metastasis, leading to reduced survival rates. Segmenting the disease course [time to recurrence, recurrence to metastasis, and post-metastasis survival (PMS)] may identify disease states for which the greatest impacts can be made to ultimately improve survival.

Objective: Evaluate real-world PMS of patients with HR-LPC/LAPC who received primary radical prostatectomy (RP) or radiotherapy (RT) with or without androgen deprivation therapy (ADT).

Patients And Methods: Electronic health records from an oncology database were used to assess PMS. Risk of death was estimated using the Kaplan-Meier method. Hazard ratios (HRs) were used to analyze the impact of treatment and time to metastasis (TTM) on PMS. Standardized mortality ratios (SMRs) were calculated for patients with HR-LPC/LAPC versus the US general male population.

Results: Overall, 5008 patients with HR-LPC/LAPC were identified, and 1231 developed metastases after primary treatment (RP, n = 885; RT only, n = 262; RT+ADT, n = 84). Age-adjusted PMS HR between the RP and RT only cohorts was 1.19 (p = 0.077) and between RP and RT+ADT cohorts was 1.32 (p = 0.078). TTM was unrelated to PMS in unadjusted (HR 1.01, p = 0.2) and age-adjusted models (HR 0.99, p = 0.3). Relative to pre-metastasis SMRs, post-metastasis SMRs increased eightfold and fivefold in patients treated with RP and RT±ADT, respectively.

Conclusions: PMS was unrelated to TTM in patients with HR-LPC/LAPC, suggesting PMS may be independent of the trajectory to development of metastases. Given PMS may be a fixed length of time, delaying the development of metastasis may improve survival in patients with HR-LPC/LAPC.