ASCO GU 2019: The Role of MRI in Targeted Biopsy
Historically, mpMRI had only been used for staging purposes after a patient had already been diagnosed with prostate cancer, however, more recently, mpMRI has become more frequently utilized for pre-biopsy disease localization and for risk stratification in men with a borderline or elevated PSA value. Dr. Taneja discussed how he has employed the use of mpMRI in his clinical practice for the last several years. He notes that greater than 95% of patients at NYU receive a mpMRI during their prostate cancer evaluation.
Dr. Taneja reviewed the data from the PROMIS trial which was one of the landmark studies that helped support the use of mpMRI in the pre-biopsy space to help risk-stratify men to determine who should undergo a targeted biopsy versus continued PSA surveillance. 576 men underwent a mpMRI of the prostate, a systematic transrectal ultrasound (TRUS) biopsy, as well as a transperineal mapping biopsy. mpMRI had a 51% positive predictive value for clinically significant (defined as ≥ Gleason 4+3=7) prostate cancer, a sensitivity of 93%, and a specificity of 41%. This is compared to systematic TRUS biopsy which had an 89% positive predictive value, a sensitivity of 48%, and a specificity of 96% for detection of clinically significant prostate cancer. The conclusions gathered from the study include the fact that MRI has greater sensitivity and negative predictive value in the detection of clinically significant prostate cancer. He noted that mpMRI is helpful in detecting clinically significant cancer that warrants treatment while minimizing the detection of clinically insignificant prostate cancer, which can often lead to overtreatment and harm to patients.
He then reviewed data from the PRECISION trial, which was a randomized comparison of TRUS biopsy versus pre-biopsy mpMRI followed by a fusion biopsy in men who were found to have PI-RADS 3-5 lesions. This trial was designed to show the non-inferiority of mpMRI for detection of clinically significant (defined as ≥ Gleason 3+4=7) prostate cancer. This study showed that in men who underwent mpMRI prior to biopsy, there was a 38% chance of detecting clinically significant prostate cancer if the man had a PI-RADS lesion that was between 3-5 and only a 9% chance of detecting a Gleason 6 prostate cancer in this cohort. The 28% of enrolled men who had a PI-RADS 1 or 2 lesion did not undergo a subsequent biopsy. He concluded that not only is mpMRI not inferior to standard TRUS biopsy for prostate cancer detection, but that it is superior and helped to avoid unnecessary biopsies in almost 1/3 of men in the trial.
Taneja concluded that the use of pre-biopsy mpMRI and MRI-targeted biopsy allows for improved high-grade cancer detection while minimizing the diagnosis of indolent prostate cancers. He believes that it is critical for practitioners to help find the proper balance of detecting high-grade cancers while avoiding the diagnosis of low-grade cancers. There remain the issues of cost, reproducibility, and quality control that are hurdles to the broad implementation of mpMRI in all men with suspicion of prostate cancer, however. He believes that future studies will help improve the adoption of this technology over time.
Presented by: Samir S. Taneja, MD, Professor of Urologic Oncology, Department of Urology, Professor, Department of Radiology, Vice Chair, Department of Urology, Co-Director, Smilow Comprehensive Prostate Cancer Center, Genito-Urologic Program Leader, NYU Perlmutter Cancer Center, Director, Urologic Oncology, NYU Langone Health, New York, New York
Written by: Brian Kadow, MD, Society of Urologic Oncology Fellow, Fox Chase Cancer Center at the 2019 American Society of Clinical Oncology Genitourinary Cancers Symposium, (ASCO GU) #GU19, February 14-16, 2019 - San Francisco, CA