Imaging and biopsy in men undergoing active surveillance

The authors aimed to determine whether multiparametric magnetic resonance imaging (mpMRI)/ultrasound fusion biopsy improves Gleason grade detection compared to systematic biopsy in active surveillance.

The authors concluded that due to the low sensitivity of mpMRI for detecting cancer grade 7 or higher, systematic biopsy will still need to be carried out in men on active surveillance.

Active surveillance is an option used to monitor the progression of prostate cancer without active treatment. The cancer is monitored using prostate specific antigen (PSA – protein elevated in the blood when prostate cancer is present) levels and biopsy (tissue samples taken from the tumour site). mpMRI/ultrasound fusion biopsy (targeted biopsy) takes 3D images of the prostate to identify areas where the cancer is to allow for a more accurate sample to be retrieved. Ultrasound fusion biopsy is then carried out using the mpMRI images and ultrasound images to accurately obtain tissues from the tumor site for biopsy. This can be used to determine cancer stage or Gleason grade (a measure of the aggressiveness of the cancer cells).

This type of targeted biopsy (TB) has been shown to be more effective in detecting high-risk prostate cancer compared to ultrasound-guided prostate biopsy (systemic biopsy, or SB). It is not as effective at detectin low-risk cancer compared to SB. The role of TB in active surveillence is not yet clear.

The aim of this study was to determine whether TB improved prostate cancer detection compared to SB in men undergoing active surveillance for prostate cancer.

230 men were included in this study. 103 men in group 1 underwent active surveillance. 54 men in group 2 underwent confirmed biopsy (biopsy taken within 1 year of diagnosis) and 73 men in group 3 underwent diagnostic biopsy (control group). The success of TB and SB at finding Gleason score 7 or above (more aggressive) tumor cells was compared.

Cancer of Gleason score 7 or higher was found in 24.3% of group 1 by TB plus SB. In comparison, it was found in 20.4% by SB alone.

This was 22.2% compared to 16.7% in group 2 and 75.3% compared to 58.9% in group 3.

In group 1, SB detected a larger amount of cancer grade 7 or higher (20.4%) than targeted biopsy (6.8%). The sensitivity of TB for detecting cancer of Gleason score 7 or higher was significantly lower than that of SB. Combining both treatments resulted in the diagnosis of otherwise undetected cancer in 3.9% of men. 

The authors concluded that due to the low sensitivity of mpMRI for detecting cancer grade 7 or higher, systematic biopsy will still need to be carried out in men on active surveillance.