Can we predict high-intensity focused ultrasound success before treatment?

This paper studied factors that might influence prostate-specific antigen (PSA) nadir levels following high-intensity ultrasound treatment in patients whose cancer has not spread beyond the prostate.

High-intensity focused ultrasound (HIFU) is a primary treatment in prostate cancer that targets and removes damaged or diseased tissue using heat energy. It has emerged as a potential focal therapy (minimally invasive technique targeting small prostate tumors) in prostate cancer that has not spread beyond the prostate (localized).

Following HIFU treatment, PSA nadir can be used to determine whether treatment has been successful. PSA nadir describes the lowest PSA level found following treatment. Previous studies suggest that PSA nadir levels of < 0.2 or 0.3ng/ml are associated with an improved cancer outcome.

This study looked at the factors that may predict a low PSA nadir after HIFU treatment, which could act as an early indicator for treatment success.

This study included 163 patients who had not previously received HIFU treatment or hormone therapy. Patients who had undergone transurethral resection of the prostate (TRUP; a surgical procedure that involves cutting away a section of the prostate gland to relieve urinary symptoms) prior to or during HIFU were included.The majority of patients analysed were considered low-risk and 90.8% received one single HIFU session. The average follow-up was 6.2 years.

Following treatment, 66.3% of the patients achieved a PSA nadir of < 0.2ng/ml. 8-year biochemical disease-free survival (survival without increasing levels of PSA) rates were 83% for those achieving a PSA nadir level < 0.2 ng/mL compared to 48% for those achieving a PSA nadir level of > 0.2 ng/mL.

Increasing prostate volume prior to HIFU was associated with 5% increased risk of having a PSA nadir > 0.2 ng/mL. Incidental finding of the cancer (finding by coincidence during examination for other reasons) prior to HIFU was associated with a 94% reduced risk having a PSA nadir > 0.2 ng/mL.

This study concluded that achieving PSA nadir levels < 0.2ng/ml following HIFU treatment could indicate treatment success in localised prostate cancer, and this may be predicted by prostate volume and incidental finding of cancer prior to treatment. 

The study was carried out in a single center, and therefore more widespread studies may be required.