Salvage of locally recurrent prostate cancer after external beam radiation using reduced-dose brachytherapy with neoadjuvant plus adjuvant androgen deprivation.

PURPOSE: Local recurrence (LR) of prostate cancer after external beam radiotherapy (EBRT) is a serious problem. Our purpose was to determine if reduced-dose salvage brachytherapy could achieve high rates of biochemical control with acceptable toxicity if combined with androgen deprivation therapy (ADT).

METHODS AND MATERIALS: Thirty-three consecutive patients with LR after EBRT were treated with salvage brachytherapy plus ADT from 1998 to 2013. All had pathologically confirmed LR, disease-free interval ≥18 months after EBRT, no distant/nodal metastasis, and International Prostate Symptom Score ≤15. Whole-gland salvage treatment was delivered using low-dose-rate (median 100 Gy with (103)Pd, n = 25) or high-dose-rate brachytherapy (30 Gy in 6 fractions over 4 weeks, n = 8) plus 4-6 months of neoadjuvant plus adjuvant ADT.

RESULTS: Fifty-five percent had high-risk disease at diagnosis. Median EBRT dose was 70.2 Gy; median prostate-specific antigen nadir was 0.8 ng/mL. Median time to recurrence was 56 months; median presalvage prostate-specific antigen was 5.0 ng/mL. Median postbrachytherapy followup was 61 months (range 7-150 months). Five and 7-year relapse-free survival, distant metastasis-free survival, and overall survival were 79% and 67%; 93% and 86%; and 94% and 85%, respectively. Freedom from late Grade 3 GU toxicity at 5 years was 85%. There were no late Grade ≥2 GI toxicities.

CONCLUSIONS: This is the largest series of salvage brachytherapy combined with neoadjuvant plus adjuvant ADT and uses reduced-dose brachytherapy. Results suggest that reduced-dose salvage brachytherapy is feasible and reasonably well tolerated when combined with ADT. Compared to prior series, this approach was associated with favorable relapse-free survival. Prospective studies of reduced-dose salvage brachytherapy plus ADT are warranted.