PSA outcomes and late toxicity of single-fraction HDR brachytherapy and LDR brachytherapy as monotherapy in localized prostate cancer: A phase 2 randomized pilot study

To evaluate the PSA outcomes and the late patient's reported health related quality of life (HRQOL) and toxicity after single-fraction High-Dose-Rate brachytherapy (HDRB) and Low-Dose-Rate brachytherapy (LDRB) for prostate cancer.

Men with low and favorable intermediate-risk prostate cancer across 3 centres were randomized between monotherapy brachytherapy with either Iodine-125 LDRB or 19 Gy single-fraction HDRB. Biochemical outcomes were evaluated using the Phoenix definition, PSA nadir and absolute PSA value <0.4 ng/mL. Toxicities and HRQOL were recorded at 24 and 36 months.

A total of 31 patients were randomized, 15 in the LDRB arm and 16 patients in the HDRB arm. After a median follow-up of 45(36-53) months, 3 patients in the HDRB arm experienced biochemical failure (p = 0.092). Nineteen Gy single-fraction HDRB was associated with significantly higher PSA nadir compared to LDRB (1.02 ± 0.66vs 0.25 ± 0.39, p < 0.0001). Moreover, a significantly larger proportion of patients in the LDRB group had a PSA <0.4 ng/mL (13/15 vs 2/16, p < 0.0001). For late Genito-Urinary, Gastro-Intestinal, and sexual toxicities at 24 and 36 months, no significant differences were found between the 2 arms. As for HRQOL, the IPSS and EPIC-26 urinary irritative score were significantly better for patients treated with HDRB over the first 36 months post-treatment (p = 0.001 and p = 0.01, respectively), reflecting superior HRQOL.

HDRB resulted in superior HRQOL in the irritative urinary domain compared to LDRB. PSA nadir was significantly lower in the LDRB group and a higher proportion of patients in the LDRB group reached PSA <0.4 ng/mL.