Confirmatory magnetic resonance imaging (MRI)-guided biopsies should be conducted to verify eligibility for prostate cancer active surveillance (AS), according to investigators.

“The findings suggest that confirmatory biopsy with MRI guidance is significantly associated with future disease upgrading of prostate cancer, especially when combined with PSA density, and should be considered as an appropriate entry point for active surveillance,” Leonard S. Marks, MD, of the University of California, Los Angeles, and colleagues wrote in JAMA Network Open.

In the study, 332 men diagnosed with Gleason grade group (GG) 1 or 2 disease upon initial transrectal ultrasound biopsy were referred for AS at a large academic medical center during 2009 to 2017. All underwent confirmatory and follow-up biopsies using an MRI-ultrasonography fusion device that captured systematic samples, targeted samples from lesions seen on multiparametric MRI, and foci of low-grade prostate cancer that could be tracked over time. The primary outcome was upgrading to at least GG3 disease during AS.

Overall, 11.7% of patients were upgraded to at least GG3 disease during follow-up. These included 7.9%, 11.4%, and 23.3% of men with confirmatory biopsy results showing normal, GG1, and GG2 histology, respectively. Men with GG2 disease at confirmatory biopsy had a nearly 8-fold higher likelihood of upgrading during AS than those with normal findings but only among those with low PSA density.

Having a PSA density of at least 0.15 ng/mL/mL correlated with 7- and 3-fold higher risks of upgrading among men with normal findings or GG1 disease on confirmatory biopsy, respectively. Normal confirmatory biopsy findings and a low PSA was linked with a lower risk of upgrading.

Confirmatory MRI-guided biopsy provided a more accurate assessment than conventional transrectal biopsy, according to Dr Mark’s team. Yet a combination of targeted and systematic biopsies are needed, they said. Targeted or systematic biopsy performed alone each would have failed to detect a large portion of clinically significant tumors in men with regions of interest: 41% and 45% of GG3 or higher disease upgrades would have been missed if either targeted or systematic biopsy, respectively, was not performed. Furthermore, nearly two-thirds of disease upgrades were detected only with tracked biopsy. Tracking was helpful both within MRI-visible regions of interest and at abnormal sites on systematic biopsy. The image-fusion device can record lesion location for future tracking.

“Combination biopsy (targeted and systematic) was a more sensitive method of detecting tumors not suitable for continued surveillance than either method alone. Repeated biopsy of previous positive coordinates (tracking) may be an important means of detecting disease upgrades and deserves further study.”

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Reference

Jayadevan R, Felker ER, Kwan L, et al. Magnetic resonance imaging–guided confirmatory biopsy for initiating active surveillance of prostate cancer. JAMA Netw Open. 2019;2:e1911019. doi:10.1001/jamanetworkopen.2019.11019