medwireNews: Magnetic resonance imaging (MRI)-guided focal ultrasound therapy is a feasible treatment for grade group 2–3 prostate cancer, indicate phase 2b trial findings published in The Lancet Oncology.
“These results support focal therapy for select patients and its use in comparative trials to determine if a tissue-preserving approach is effective in delaying or eliminating the need for radical whole-gland treatment in the long term,” say Behfar Ehdaie (Memorial Sloan Kettering Cancer Center, New York, USA) and co-authors.
The study recruited men aged at least 50 years with unilateral, MRI-visible, and intermediate-risk prostate adenocarcinoma. This was defined as a prostate-specific antigen (PSA) level of 20 ng/mL or less, grade group 2 or 3 disease, and a tumor classification of T2 or lower.
Overall, 101 men aged a median of 63 years and with a median PSA of 5.7 ng/mL received focused ultrasound energy titrated to achieve a temperature of 60–70°C for tissue ablation of their index lesion and a planned margin of at least 5 mm, the investigators explain.
At 6 months, 95% of the patients were free from grade group 2 or more advanced disease on a MRI-targeted and systematic biopsy of the treated area of their prostate, as were 88% of 89 patients who underwent biopsy after 24 months.
“Our findings met the original prespecified criteria for effectiveness,” Ehdaie et al report.
Of the 11 men who had grade group 2 disease or worse within the treatment site at 24 months, two had grade group 3, one had grade group 4 and two had grade group 5 disease.
The researchers also used the combined prostate biopsy protocol to look for disease in the whole gland. At 6 months, 76% of the 101 men were free from grade group 2 or worse disease, as were 60% of the 98 patients assessed at 24 months.
The team notes that 19% of men had grade group 2 or more severe prostate cancer outside the treatment area at the 6-month biopsy but suggests that “[g]iven the short interval between biopsies, rather than representing new sites of cancer, these men most probably harboured these additional undetected cancers before treatment.”
Analysis shows that PSA levels decreased after focal ultrasound, stabilized at around 6 months and rose again after 24 months.
Compared with baseline, at 24 months after treatment the patients had “slightly worse” scores for erectile function, intercourse satisfaction, and overall satisfaction.
International Prostate Symptom Score measures of lower urinary tract symptoms and quality of life were “similar” at the two timepoints, with none of the 18 patients who had grade group 2 or less severe incontinence requiring a pad.
“These functional outcomes compare very favourably to patient-reported outcomes after whole-gland treatments, such as radical prostatectomy and radiotherapy, which, although effective, are associated with substantial and persistent side-effects that impact quality of life,” write Ehdaie et al.
There was one grade 3 adverse event (AE) related to the procedure (urinary tract infection) and grade 2 or less severe hematuria and urinary retention occurred in 24% and 15% of patients, respectively. There were no serious treatment-related AEs, the investigators say.
The team acknowledges that 24-month biopsy alone “is not a sufficient surrogate endpoint for metastases or cancer-specific death” and that without a comparative treatment arm “we cannot estimate the long-term clinical benefit of treating these men rather than following on an active surveillance protocol.”
Nevertheless, the authors emphasize that “most” of the men in their study would otherwise have undergone radiotherapy or surgery but just 15% went on to have grade group 3 or more severe disease during the follow-up period.
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