Prospective trial on focal treatment with hemigland brachytherapy in low-risk prostate cancer: A negative study

To determine whether hemi-gland seed brachytherapy (HGBT) is as effective as whole-gland seed brachytherapy (WGBT) in patients with single-lobe, low-risk and favorable intermediate-risk prostate cancer (PCa).

Phase II clinical trial in patients with low- and favorable intermediate-risk PCa with HGBT. Enrolment took place between 2016 and 2020. All patients (n = 38) underwent HGBT with iodine-125 (¹²⁵I) seeds. Inclusion criteria: single-lobe prostate cancer, ≤ 2 positive cores in one lobe (≥ 10 core samples), < 50% core invasion, Glea-son ≤ 7 (3 + 4), non-visible or unilaterally visible tumor. Patient-reported expanded prostate cancer index (EPIC-26) questionnaire was administered to assess quality of life (QoL). Treatment outcomes were compared with a historical cohort of patients (n = 700), who underwent transperineal, ultrasound-guided ¹²⁵I WGBT between 2000 and 2012.

The mean age was 64.9 years (range, 50-78), the mean baseline prostate-specific antigen (PSA) was 6.12 ng/ml (range, 1.53-10), and the mean nadir was 1.4 ng/ml (range, 0.17-4.24). Most patients (37/38) had Gleason 3 + 3. The mean follow-up was 71.4 months (range, 44-93). Seventeen patients developed biochemical relapse, and 14 presented local clinical progression (contralateral, n = 9, ipsilateral + contralateral, n = 4; and regional, n = 1). Salvage therapy was: contralateral low-dose-rate (LDR) BT (n = 6), high-dose-rate (HDR) BT (n = 2), nodal radiation therapy (RT) + hormonotherapy (n = 2), hormonotherapy alone (n = 1), and prostatectomy (n = 1). Thirty-five patients (92.1%) remained alive (12 with biochemical failure) at the final follow-up, while three patients died of other causes. A slight impairment was observed on all EPIC domains (urinary incontinence, urinary obstruction, bowel, sexual, and hormonal summaries). Compared with the WGBT cohort, urinary irritative/obstructive scores were significantly lower (p = 0.002). At 5 years, biochemical relapse-free survival (BRFS) was 54% in the HGBT group vs. 95% in the WGBT cohort.

In this trial, patients treated with hemi-gland brachytherapy had significantly higher biochemical failure and contralateral relapse rates than a historical cohort of patients treated with WGBT. Larger, well-designed clinical trials are needed to better assess the efficacy of HGBT in the treatment of low-risk PCa.