In-field prostate cancer recurrence following radical prostatectomy and salvage radiation

Objective: To define the natural history, patterns of recurrence and treatment modalities for local prostate cancer (PCa) recurrence following radical prostatectomy (RP) and radiation therapy (RT), and to investigate factors that could predict metastasis-free survival (MFS) in this unique patient population.

Methods: We queried a prospectively maintained PCa registry to identify men developing in-field recurrence (IFR) following RP and RT from 2008 to 2021 at a single institution. IFR was defined as biopsy-proven recurrent PCa or the presence of persistent positron emission tomography-avid lesions in the prior radiation field without evidence of metastasis. Cox regression was conducted to determine predictors of MFS. Kaplan-Meier methods were used to calculate MFS, cancer-specific survival (CSS) and overall survival (OS) for patients in three primary therapy categories: cryoablation, androgen deprivation therapy (ADT) alone, and surveillance.

Results: Of 4575 patients from our registry, 108 (2.3%) with IFR were identified. The median (interquartile range [IQR]) time to IFR from salvage treatment was 78 (50-126) months. A total of 29 patients (26%) were managed with cryoablation, 23 (21%) with ADT, and 28 (25%) with surveillance. The median (IQR) follow-up was 76 (48-100) months. There were no statistically significant differences in MFS (P = 0.67) or OS (P = 0.07) among the three primary treatment cohorts. Patients treated with ADT or cryoablation had longer CSS compared to patients managed with surveillance (P = 0.047).

Conclusions: We found that IFR may present years after completion of primary treatment for PCa. While curative management strategies may be attempted, local and distant metastatic recurrence is common and often requires systemic therapy.