Since the PSA assay hit the mainstream for prostate cancer screening in the late 1980's, detection of prostate cancer has allowed for various levels of stratification for treatment, including active surveillance. This modality for prostate cancer treatment has not been widely adopted based upon the imprecision of the risk status based upon TRUS-guided prostate biopsy.
A recent trial examined 124 men with favorable risk prostate cancer who were assigned to active surveillance. The trial sought to describe the extent to which repeat TRUS biopsy can detect and rule out clinically relevant prostate cancer in men with favorable risk cancer.
In this trial, repeat TRUS biopsy failed to detect 80% of clinically relevant cancers, with a negative predictive value of 23-60%. The authors state that from this unique study, their data will allow clinicians to discuss conservative approaches for presumed favorable risk prostate cancer. Importantly, the imprecision of testing and biopsy may be directly related to the choice of active surveillance.
The authors conclude that in patients to be considered for active surveillance, they should undergo template guided perineal prostate biopsies, since this modality is more likely to detect cancer than TRUS biopsies. Ultimately, there may be a selection bias for diagnosis of higher volume disease if a larger number of biopsies overlap and sample the cancerous lesion more than once, which would provide a false-positive result.
Reference: Barzell WE, Melamed MR, Cathcart P, et al. Identifying candidates for active surveillance: an evaluation of the repeat biopsy strategy for men with favorable risk prostate cancer. Journal of Urology 2012;188:762-768.