Multiparametric MRI (mpMRI) of the prostate is effective in helping men avoid unnecessary prostate biopsies, according to research presented on Tuesday.
In a study presented by Wulphert Venderink, MD, Radboud University Medical Centre, Nijmegen, The Netherlands, researchers found that more than 50 percent of patients suspected of having prostate cancer were able to avoid biopsy because of negative findings on mpMRI.
"MRI of the prostate has become such a big game changer because so many studies have showed it to be superior to the alternative — 12-core transrectal ultrasound [TRUS] guided biopsies," Dr. Venderink said. "TRUS comes with the risk of infection, and it under detects clinically significant prostate cancers and over detects insignificant cancers."
In this study Dr. Venderink and his colleagues retrospectively reviewed patients having mpMRI in their institution between January 2012 and December 2017. They included patients who were suspected of having prostate cancer and had either a history of negative TRUS biopsy or were biopsy-naïve.
Lesions were classified using the ACR's Prostate Imaging Reporting and Data System (PI-RADS) by one of eight different radiologists‚ each with a varying amount of experience. The primary outcome was a negative mpMRI, defined as an index lesion classified as PI-RADS <3.
"In our hospital we do not biopsy lesions that are classified as PI-RADS 1 or 2," Dr. Venderink said. "We also do not biopsy lesions that are classified PI-RADS 3 in combination with a low PSA density [below 0.15 ng/ml]."
The study included 4,259 men with a median age of 64 years and a median PSA of 8.5 ng/ml. Slightly less than half (47.9 percent) had a history of previously negative TRUS biopsy, while the remaining men (52.1 percent) were biopsy-naïve.
More than half of the men (53.6 percent) were classified as having a negative mpMRI (PI -RADS <3) and avoided biopsy. Of the remaining men, 12 percent were classified as PI-RADS 3, 15 percent as PI-RADS 4, and 19 percent as PI-RADS 5. Furthermore, the researchers determined that 5.3 percent of the men imaged were classified as PI-RADS 3 and had a PSA density below 0.15 ng/ml, meaning they avoided biopsy as well.
Dr. Venderink and his colleagues found that the number of men with negative mpMRIs didn't substantially differ from year to year. They also noted that when broken down into cohorts (biopsy-naïve men and those with previously negative biopsies), the percentage of men with negative mpMRIs was similar.
According to Dr. Venderink, of those patients with a positive mpMRI, radiologists were able to detect clinically significant prostate cancers with targeted biopsies in 75 percent of them. "So, MRI not only allows patients to avoid biopsy, it also allows us to target a lesion and biopsy it with two needle cores instead of randomly performing 12 biopsies," he said.
The researchers also noted that just 9 of the 2,281 patients with a negative mpMRI (0.4 percent) had a clinically significant prostate cancer detected after a median period of 29 months.
"Our research underlines the importance of using MRI in men who are suspected of having prostate cancer," Dr. Venderink said. "It also demonstrates that PI-RADS is an adequate tool to select patients who need subsequent targeted biopsy, and those who may safely avoid biopsy."