Pathologic failure and salvage approaches following focal therapy for localized prostate cancer.

BACKGROUND: Focal therapy (FT) is an emerging treatment modality for localized prostate cancer. However, limited data are available regarding the patterns of oncologic failure post-FT. This study aims to characterize the features of oncologic failure and salvage strategies following FT. METHODS: Patients presenting with pathologic failure (PF) after receiving FT (cryotherapy, High-intensity focused ultrasound, or irreversible electroporation) for intermediate-risk prostate cancer were selected from a prospective registry between 2018 and 2023. All patients underwent protocol-based follow-up, including PSA testing, multiparametric MRI, and mandatory biopsy. The primary outcome was PF, defined as biopsy-confirmed Grade Group ≥2 cancer post-treatment. Failures were classified as in-field or out-of-field based on lesion location relative to the ablation zone. RESULTS: This study included 101 patients who underwent primary FT, with a median follow-up of 16.5 months. PF occurred in 18 patients (17.8%). Failures included 7 in-field, 9 out-of-field, and 2 involving both locations. Notably, 50% of recurrences had no suspicious findings on MRI, and 67% occurred without meeting Phoenix PSA criteria for biochemical recurrence. Failures were typically low-volume (mean longest positive core length 4.8 mm), and 11 were detected within the first 12 months of follow-up. Among those with PF, definitive salvage treatments included repeat FT (55.6%), active surveillance (16.7%), radical prostatectomy (11.1%), whole-gland ablation (5.6%), and radiation therapy (11.1%). CONCLUSIONS: Focal therapy is increasingly used for localized prostate cancer, but many failures occur without PSA rise or imaging abnormalities. These findings suggest that although PSA testing and imaging are valuable for surveillance after FT, biopsy remains essential.