Transrectal prostate biopsies without MRI may suffice in cancer workup of some patients

Transrectal ultrasound-guided biopsies (TRUS-biopsies) yield a high detection rate of clinically significant prostate cancer for men with palpable tumours and high prostate-specific antigen (PSA), as reported in a study, suggesting that not all men require a prebiopsy magnetic resonance imaging (MRI).

Nevertheless, MRI has its merits, according to the investigators. It can reduce the number of unnecessary biopsies, especially among men with clinically unapparent tumour and PSA <20 ng/ml.

TRUS-biopsies are the gold standard for diagnosis and identification of prostate cancer. But the procedure, in combination with PSA, has been getting a bad rap for the high risk of either missing a diagnosis or overdetection of an insignificant disease. Diagnosing clinically irrelevant disease, according to the investigators, is especially problematic, as it may cause harm to the patient both physically and mentally. [Urol Int 2007;78:313-317; N Engl J Med 2018;379:2319-2329]

“MRI of the prostate has been introduced as an additional tool in the diagnostic workup,” based on studies showing that prebiopsy imaging can increase sensitivity and specificity to rule out significant disease, the investigators said. [Lancet 2017;389:815-822; N Engl J Med 2018;378:1767-1777; JAMA Netw Open 2018;1e180219]

“As a result, international guidelines now recommend MRI before prostate biopsies for all men referred for suspicion of prostate cancer. However, the trials demonstrating a benefit from MRI applied the strategy to selected patients which may affect the generalizability of the results when transferred to men referred for biopsies in the general population,” they pointed out. [J Urol 2020;203:706-712; https://uroweb.org/guideline/prostate-cancer]

In the current study, the investigators assessed how systematic TRUS-biopsies perform in detecting clinically significant prostate cancer. They used data from the nationwide Danish Prostate Cancer Registry (DaPCaR) and looked at 39,886 men (median age 68.1 years) with elevated PSA (median 10 ng/ml) who underwent initial TRUS-biopsies over 20 years.

The diagnostic hit rate was 40.8 percent for clinically significant disease, which was defined as any biopsy containing Gleason score ≥3–4 as in the PRECISION trial. [Urology 2021;doi:10.1016/j.urology.2021.06.007; N Engl J Med 2018;378:1767-1777]

Men with PSA >20 ng/ml and ≥cT2 were 75-percent more likely to be diagnosed with clinically significant prostate cancer in the first TRUS biopsy-set. Meanwhile, those with cT1 tumours and PSA <20 ng/ml had about a 58-percent higher likelihood of having nonmalignant histology.

“Regardless of the age group, nonmalignant histology is the most frequent biopsy result in men with cT1 and PSA <20 ng/ml and this group of men seems to be an optimal candidate for prebiopsy MRI, which is in line with the selection criteria in the PRECISION trial,” the investigators noted.

“An important goal is still to reduce the number of unnecessary biopsies. Optimal selection for prebiopsy MRI, based on data such as included here, could reduce the number of MRIs needed which may [factor in the future] as we switch biopsy strategy to an MRI pathway,” they added.

The study was limited by the high number of exclusions based on missing information.