Feasibility and preliminary outcome of salvage combined HDR brachytherapy and external beam radiotherapy (EBRT) for local recurrences after radical prostatectomy

Abstract

Purpose: Feasibility of combined fractionated intensity modulated brachytherapy (IMBT) and external beam radiotherapy (EBRT) as well as the effect of local dose escalation was investigated in a non-randomized retrospective observation trial for histologically-proven macroscopic local recurrences of prostate cancer after radical prostatectomy.

Methods and materials: Thirty-five patients with transrectal ultrasound (TRUS) detectable tumors were treated. Applied dose per IMBT fraction was 15 Gy, prescribed on the target (TRUS visible tumor) surface. For the first 21 patients, two fractions of IMBT were delivered in 2 weeks interval, complementary to 30 Gy EBRT to the small pelvis. Further, as second step of dose escalation, 14 patients were treated with 2 x 15 Gy IMBT combined with 40 Gy EBRT. The total treatment time was 4 and 5 weeks, respectively.

Results: PSA was decreased in 34 out of 35 patients post-therapeutically. After a mean follow-up of 27 months, 32 out of 35 patients are alive. However, in 67% of the patients, we observed postimplant PSA elevation with or without detectable local and/or systemic progress. The mean duration of biochemical non-evidence of disease (bNED) after radiation was 12 months for all patients (31% in the 30 Gy group and 42% in the 40 Gy group). No RTOG/EORTC grade III or IV side effects were registered during/after radiotherapy.

Conclusion: Combined EBRT and IMBT-boost of TRUS detectable recurrences of prostate cancer after radical prostatectomy seems to be a feasible method of salvage treatment. These early results need to be confirmed by further prospective randomized trials and by longer follow-up in all dose groups.