Failure-free survival following brachytherapy alone or external beam irradiation alone for T1–2 prostate tumors in 2222 patients: results from a single practice

Abstract

Purpose: To evaluate failure-free survival (FFS) for brachytherapy (BT) alone compared to external beam radiotherapy (EBRT) alone for Stage T1–2 Nx-No Mo patients over the same time period by a single community-based practice in the prostate-specific antigen (PSA) era. Materials and Methods: The database of Arizona Oncology Services (a multiphysician radiation oncology practice in the Phoenix metropolitan area) was reviewed for patients meeting the following criteria: ( 1) T1 or T2 Nx-No Mo prostate cancer; ( 2) no prior or concurrent therapy including hormones; ( 3) treatment period 12/88–12/95; and ( 4) treatment with either EBRT alone or BT alone ( 125I or 103Pd). This yielded 1527 EBRT and 695 BT patients; no patients meeting the above criteria were excluded from analysis. Median follow-up for EBRT patients was 41.3 months and, for BT patients, 51.3 months. Patients were not randomized to either therapy but rather received EBRT or BT based upon patient, treating, and/or referring physician preference. PSA failure was defined according to the ASTRO consensus guidelines. The median patient age was 74 years for both groups. Results: Failure-free survival at 5 years for EBRT and BT are 69% and 71%, respectively ( p = 0.91). For T stage, no significant difference in FFS at 5 years is observed between EBRT and BT for either T1 (78% vs. 83%, p = 0.47) or T2 (67% vs. 67%, p = 0.89) tumors. Analysis by Gleason score shows superior outcomes for Gleason 8–10 lesions treated with EBRT vs. BT (5-year FFS 52% vs. 28%, p = 0.04); outcomes for lower grade lesions (Gleason 4–6) when analyzed by Gleason score alone do not significantly differ according to treatment received. Patients with initial PSA values of 10–20 ng/dL have an improved FFS with EBRT vs. BT at 5 years (70% vs. 53%, p = 0.001); outcomes for patients with initial PSA ranges of 0–4 ng/dL, of > 4–10 ng/dL, and > 20 ng/dL did not differ significantly by treatment received. FFS was also determined for presenting Gleason score/PSA combinations; all Gleason combinations in the initial PSA range >10–20 ng/dL had superior outcomes with EBRT compared to BT, and this reached statistical significance for Gleason scores of 2–4 (72% vs. 58%, p = 0.026), Gleason 7 (67% vs. 28%, p = 0.002), and Gleason 8–10 (63% vs. 23%, p = 0.05). Conclusion: In our patient population, either EBRT or BT appear equally efficacious for patients with T1/T2 disease with Gleason scores ≤ 6 or PSA ≤ 10 ng/dL. Patients with presenting Gleason scores of 8–10 or PSA > 10 ng/dL (but ≤ 20 ng/dL) appear to fare significantly worse with BT alone compared to EBRT alone. Neither EBRT nor BT alone was particularly effective for patients with a presenting PSA > 20 ng/dL, as would be anticipated from the significant risks of occult distant metastasis in this group. To our knowledge, this is the first report comparing the outcome of EBRT and BT treatment in patients treated concurrently by a single group, and these results, achieved in a community-based practice, compare favorably to data from academic centers regarding external beam, brachytherapy, or surgical outcomes and should be generalizable to the community at large.