Reirradiation salvage radiotherapy for recurrent prostate cancer after primary low-dose brachytherapy.

Purpose: Local recurrence of prostate cancer after low-dose rate brachytherapy is a clinical problem with limited salvage treatment options. This prospective study evaluated the tolerability and outcome of salvage external beam radiation therapy (S-EBRT) for locally recurrent prostate cancer after primary low-dose rate prostate brachytherapy (LDR-BT).

Materials And Methods: Between October 2012 and 2022, 18 patients with biopsy-proven locally recurrent prostate cancer after primary LDR-BT and received S-EBRT. We evaluated biochemical failure (BF), overall survival (OS) and acute/late gastrointestinal and urinary toxicities (CTCAE v5.0 or CTCAE v4, only before 2017).

Results: Median follow-up was 32 months (range, 5-124). The median age was at S-EBRT 68 years (range 59-79). 34% (6/18) were low risk, 44% (8/18) intermediate risk, 5% (1/18) high risk, and 17% (3/18) not specified. All patients were treated with IMRT/VMAT and received 60 Gy (2.5 Gy/fraction) to the prostate and 40% (7/18) 55.2 Gy (2,3 Gy/fx) to the seminal vesicles. 56% received ADT The 3-year OS and biochemical relapse-free survival after S-EBRT were 100% and 89%, respectively, with a median PSA nadir 0,035 ng/mL (0,01-0,34). Acute cystitis was present in 72% (13/18) of patients (27% of Grade > 2). Urethritis was present in 78% (14/18) patients (16% of cases Grade > 3), and acute rectitis occurred in 22% (4/18) of patients (no cases Grade > 3).

Conclusions: Our data suggest that the treatment of locally recurrent prostate cancer with S-EBRT could provide adequate disease control safely and be used as an additional treatment in the natural history of prostate cancer patients. However, the results are still early and the sample is small; larger studies with longer follow-up would be mandatory.