EAU 2017: Con – mpMRI targeted biopsies are sufficient

London, England (UroToday.com) In this session, Dr. Pinto discussed his rationale for why it is becoming increasingly difficult to defend concomitant transrectal ultrasound-guided prostate biopsy (TRUS-B) at the time of MRI-guided targeted biopsy (TB). Currently TRUS-B is standard of care in the diagnosis of prostate cancer. However, it has low sensitivity and specificity for detecting clinically significant cancer. This is perhaps best characterized by the finding that it may only sample 0.4% of the gland (Salami et al. BJUI 2015), is difficult to sample anterior and apical gland (De Gorski et al. J Urol 2015), and is less effective in patients with prior negative biopsy (Vourganti et al. J Urol 2012). In fact, prostate cancer is the only solid tumor diagnosed without image guidance, which results in missing clinically significant cancers and finding indolent lesions.

Multiparametric magnetic resonance imaging (mpMRI) holds promise for improving prostate cancer detection; the sensitivity and specificity approach 90%. In a large analysis (Siddiqui et al., JAMA 2015;313:390) MRI TB diagnosed 30% more high risk cancers and 17% fewer low risk cancers. Adding TRUS-B to TB detected only 29 more clinically significant (Gleason Group 2 or higher) cancers. Moreover, a recent meta-analysis demonstrated superiority of TB over TRUS-B in detecting clinically significant cancer (Wegelin et al,. Eur Urol 2016). While the percentage changes with definition of clinically significant cancers, data suggest that can be as low as 2-4%. This may be particularly true in patients with prior negative biopsy for whom repeat TRUS-B performs poorly relative to TB. These are reflected in the AUA guidelines which suggest “highly considering” MRI in any patient with a prior negative TRUS-B who has persistent clinical suspicion for prostate cancer.

Dr. Pinto briefly considered the cost implications of adopting an MRI-based approach to prostate cancer diagnosis. Although TB has more up-front cost, long-term cost benefits can be realized due to improved diagnostic accuracy. In fact, a formal cost analysis determined that MRI was less expensive or comparable in cost to TRUS-B in lower prevalence cohorts of prior negative biopsy patients (Lotan et al, Urol Oncol 2015).

In conclusion, Dr. Pinto suggested that MRI TB is “the right tool in the right hands” because it has superior accuracy in identifying clinically significant prostate cancer. TRUS-B is likely to detect clinically insignificant tumors potentially leading to overtreatment. Therefore, in facilities with appropriate expertise, MRI TB has already become the new diagnostic standard.

Speaker(s): P. Pinto, Washington, DC, USA

Written By: Benjamin T. Ristau, MD, SUO Fellow, Fox Chase Cancer Center, Philadelphia, PA

at the #EAU17 - March 24-28, 2017- London, England

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