Neutron beam radiotherapy for recurrent prostate cancer following radical prostatectomy

To evaluate the effectiveness of neutron beam radiotherapy (NXRT) to treat recurrent prostate cancer following radical prostatectomy (RP).

Twenty-five patients who failed RP received NXRT at our institution. The pathological stages ranged from T2c-T3c, with 16 patients having either seminal vesicle involvement and/or nodal metastases. Sixteen patients also received neoadjuvant hormones. Freedom from relapse (FFR) was defined by an undetectable PSA (PSA < or =0.2). Median follow-up was 27 months, with no patients lost to follow-up.

Postneutron PSA became initially undetectable in 84% of patients. The actuarial FFR is 36% at 3 years. Nine patients remain NED, 12 patients have an elevated PSA only, 2 patients have clinical recurrence, and 2 patients are dead of prostate cancer. Pre-NXRT PSA levels of < or =1.0 vs. >1.0 predicted for outcome, with a FFR at 3 years of 76 vs. 14% (p = 0.003). Patients with a persistently elevated PSA following RP were not effectively salvaged by NXRT, with a 12% FFR at 3 years compared to a 62% FFR for patients whose PSA initially normalized following RP (p = 0.03). There was no difference in treatment outcomes based on fields encompassing pelvic nodes vs. fields directed to the prostatic fossa only. There were no severe (RTOG Grade 3) late complications.

NXRT is an effective salvage treatment for carefully selected patients. This group includes patients whose PSA initially normalized following RP, and whose pre-NXRT PSA < or =1.0.