(P069) Gleason 7 Prostate Adenocarcinoma Treated With High- or Low-Dose-Rate Brachytherapy: Impact of External Beam Radiotherapy and/or Androgen Deprivation Therapy

Julian Johnson, MD, Charles Hsu, I-Chow Hsu, MD, Vivian K. Weinberg, PhD, Alexander Gottschalk, MD, PhD, Barby Pickett, MS, Mack Roach; University of California, San Francisco; Texas Oncology

PURPOSE: To determine the impact of hormone therapy (HT) and/or external beam radiotherapy (EBRT) on prostate-specific antigen (PSA) nadir (nPSA) in patients with Gleason score (GS) 3 + 4 or 4 + 3 prostate cancer treated with low-dose-rate (LDR) or high-dose-rate (HDR) brachytherapy (BT) at a single institution.

MATERIALS AND METHODS: A total of 148 men were retrospectively identified with GS 7 (21% GS4 + 3, 79% GS3 + 4) cT1–T2cN0 prostate cancer receiving LDR (76%) or HDR (24%) BT as a component of treatment. LDR or HDR monotherapy was administered to 29% (EBRT was administered in 58%; HT was administered to 51%). Median follow-up from BT until last PSA or death was 72 months (range: 1–141 mo). nPSA was defined as current postimplant PSA nadir as of last visit. Disease failure was defined as PSA failure, local recurrence, metastasis, or salvage therapy.

RESULTS: Median time to nPSA was 43.4 months vs 29.8 months for patients treated with LDR vs HDR (P = .03). Patients treated with HDR were more likely to have T2 disease (P = .01) and had higher median baseline PSA (8.6 vs 6.2 ng/mL; P = .004). Patients treated with HDR were more likely to receive HT (42% vs 69%; P = .01) but not EBRT (54% vs 61%; P = .56). There was no statistically significant difference between nPSA after LDR vs HDR (median: 0.1 vs 0.1 ng/mL; P = .27). Median nPSA after LDR for GS 3 + 4 vs 4 + 3 was 0.1 ng/mL and 0.05 ng/mL, respectively (P = .32). Median nPSA after HDR for GS 3 + 4 vs GS 4 + 3 was 0.1 vs 0.06 ng/mL, respectively (P = .62). Treatment with HT resulted in a median nPSA of 0.045 vs 0.1 ng/mL (P < .0001). EBRT resulted in median nPSA of 0.06 ng/mL vs 0.1 ng/mL (P = .05). Patients treated with LDR brachytherapy had a lower nPSA if treated with HT (0.05 ng/mL vs 0.1 ng/mL; P = .0002). HT did not result in a lower nPSA in patients treated with HDR (P = .18). There was a statistically significant lower nPSA among LDR patients when combined with EBRT vs no EBRT (0.05 ng/mL vs 0.1 ng/mL; P = .003) but not among HDR patients (P = .52). Freedom from disease failure rate at 5 years was 92% vs 94% for LDR vs HDR, respectively (P = .00). There was no statistically significant difference with ADT (95% vs 89%; P = .33) or with EBRT (93% vs 91%; P = .37).

CONCLUSIONS: nPSA has been related to biochemical progression–free survival, freedom from metastasis, and death from prostate cancer. BT with either EBRT or HT achieves a lower PSA nadir. There was no difference in disease failure. Longer follow-up may be necessary to see differences in disease failure in this population.

Proceedings of the 97th Annual Meeting of the American Radium Society- americanradiumsociety.org