Cryotherapy directed to the cancerous part of the prostate may be an effective and less invasive treatment option for men with intermediate-risk, unilateral prostate cancer, without the common side effects of traditional approaches, a small study suggests.

The procedure was well tolerated, and 80% of the men were free of clinically significant disease at six and 18 months post-treatment, its researchers reported. Still, larger studies are needed to better assess the therapeutic potential of partial cryotherapy in this patient population, they added.

The study, “18-Month Outcomes of Hemi-Gland Cryoablation Of Prostate Cancer Evaluated By MRI-Guided Biopsy,” was published in the Journal of Urology. These findings were to be presented at the American Urological Association 2020 Annual Meeting, which was canceled due to the COVID-19 pandemic.

Cryotherapy, also known as cryoablation, involves ultrasound-guided delivery of very cold temperatures to freeze and kill prostate cancer cells. This approach was the first focal therapy for prostate cancer, meaning it targets the cancerous portion of the gland to minimize damage to healthy surrounding tissue.

It is indicated as a first-line treatment for early-stage or intermediate-risk prostate cancer, or as salvage therapy after other treatment approaches have failed.

Cryotherapy is less invasive than radical prostatectomy (surgical removal of the whole prostate), usually resulting in less blood loss, a shorter hospital stay, shorter recovery period, and less pain.

It is also associated with fewer side effects, including erectile dysfunction and incontinence, which are common after prostatectomy or radiation therapy. However, data on the long-term effectiveness of cryotherapy are still limited.

Clinical researchers at University of California, Los Angeles (UCLA) evaluated the long-term safety and effectiveness of hemi-gland, or partial, cryotherapy in 56 men with intermediate-risk, unilateral prostate cancer.

Cryotherapy’s effectiveness was assessed with magnetic resonance imaging (MRI)-guided biopsies up to 18 months after treatment, the longest follow-up yet available with this method.

Participants underwent a systematic biopsy, collecting samples throughout the prostate, before treatment. They also had a biopsy targeting the cancer region at six months after treatment, and a systematic biopsy again at 18 months. All treatment and monitoring procedures were conducted at UCLA.

At each time point, the levels of prostate-specific antigen (PSA), a biomarker of prostate cancer, and percent-free PSA were measured. Percent-free PSA shows how much PSA circulates freely in the blood compared with total PSA levels, which include PSA attached to blood proteins. Lower percentages in this measure indicate a greater chance of prostate cancer.

At six months, clinically significant prostate cancer was detected in 12 men (21%), with three of them (5.4%) showing cancer at the opposite side of the prostate (contralateral cancer).

Five (22%) of the 23 men who underwent systematic biopsy at 18 months had clinically significant disease, with two of them (8.7%) at the opposite site of the gland.

Median PSA levels significantly dropped from 6.6 pre-treatment to 2.0 at 18 months post-treatment, and median percent-free PSA increased from 14 to 18, indicating a lower risk of cancer.

Six men (11%) were re-treated with hemi-gland cryotherapy, and two (4%) underwent salvage brachytherapy, a type of internal radiation therapy. There were no reports of serious adverse events throughout the study.

These findings highlighted that hemi-gland cryotherapy was well-tolerated and effectively eliminated clinically significant cancer in 80% of men after six and 18 months, suggesting long-term effectiveness.

The presence of contralateral cancer in about 9% of men at 18 months “suggests that both targeted and systematic biopsies are advisable at long-term follow-up,” the researchers wrote.

In a UCLA news release, the team noted that while these results are very encouraging, they are still preliminary and further research on the benefits of hemi-gland cryotherapy in this patient population is needed.