A clinical trial will test whether partial prostate ablation matches radical prostatectomy in effectiveness — with fewer early side effects.
Destroying part of the prostate to treat prostate cancer may be just as effective as removing the entire organ, but without many of the distressing side effects that tend to accompany the more invasive operation, according to investigators in the United Kingdom.
Based on the results of a feasibility study, the researchers are moving forward with a randomized controlled trial that will compare partial prostate ablation with radical prostatectomy in patients with intermediate-risk prostate cancer, according to a presentation at the American Urological Association’s 2017 Annual Meeting, held in May in Boston.
In partial ablation, the portion of the prostate gland containing the tumor is destroyed through one of several types of “focal therapies,” while the rest of the organ is left intact. In the feasibility study, investigators used high-intensity focused ultrasound to achieve partial prostate ablation. In the randomized trial, they hope to also include cryotherapy (freezing), focal brachytherapy (radiation) and vascular targeted photodynamic (light-activated) therapy.
The investigators have hypothesized that partial ablation using minimally invasive therapies can not only achieve organ preservation but can also reduce the incidence of side effects, allowing men to maintain good voiding and sexual function without any compromise to cancer health outcomes. “The data certainly suggest fewer side effects in the partial ablation arm early on,” said lead study author Tom Leslie, M.B., Ch.B, D.Phil, a consultant urological surgeon at Oxford University Hospitals. “The aim of the study is to see whether these benefits can be balanced with the oncological outcomes.”
The phase 3 PART (Partial prostate Ablation versus Radical prosTatectomy) trial would be the first to compare the two procedures in the context of intermediate-risk, unilateral, clinically significant, localized prostate cancer and could improve understanding of how to treat this disease, the researchers said. Previous studies generally assessed these treatments in low-risk prostate cancer, which can alternatively be treated with watchful waiting.
The feasibility study was conducted at five large urology clinics in the U.K. and targeted men amenable to partial ablation or radical prostatectomy. The group included some men whose cancerous cells were abnormal enough to receive a score of 4 on the five-point Gleason scale. Other participants had contralateral insignificant (very low-risk) disease. The patients were diagnosed by multiparametric magnetic resonance imaging (MRI), along with biopsy, and randomized to receive either partial ablation or prostatectomy. “When we were designing this study, the diagnostic pathway was rapidly evolving, so we tried to move with the times by incorporating prostate MRI, targeted biopsies and fusion biopsies (which combine MRI and ultrasound images),” Leslie said.
The investigators randomized half the men to partial ablation and half to radical prostatectomy, and collected data on quality-of-life factors, primary treatment failure (the need for whole-gland ablation or secondary therapy), long-term side effects, disease progression and diseasecaused mortality. According to Leslie, they also paid attention to cases in which focal therapies were tried but then prostatectomy or radiotherapy were required due to progressing disease.
The feasibility trial recruited the targeted 80 patients. Half of the men who were considered wanted prostatectomy and therefore were not included in the study. Others preferred brachytherapy, cryoablation or chemotherapy and also could not participate. “These were men who couldn’t be randomized because they knew what they wanted, and that’s perfectly fair,” Leslie said. Ultimately, 52 men were randomized; however, in a future analysis of the study, the number of men evaluated will increase to 82, once researchers have been able to follow some later recruits, Leslie said.
Initial responses suggested fewer side effects for patients who received partial ablation, compared with radical prostatectomy. However, as the study progressed, there was no significant difference in patient perception of essential function and quality of life, particularly concerning erectile dysfunction and incontinence. “The overall impression was that, early following treatment, quality of life was improved in the partial ablation arm, but as time went, the two arms came together — i.e., as the surgical patients recovered, so did their quality of life,” Leslie said.