Adding MRI to a standard tissue biopsy appears to enhance the accuracy of a prostate cancer diagnosis, new research finds.
The study, led by researchers at the U.S. National Cancer Institute (NCI), found that combining the two methods cut the rate of "underdiagnosis" by more than half, compared to use of either MRI or biopsy alone.
"With the addition of MRI-targeted biopsy to systematic biopsy, we can now identify the most lethal cancers within the prostate earlier, providing patients the potential for better treatment before the cancers spread," study senior author Dr. Peter Pinto said in an NCI news release. Pinto is with the Urologic Oncology Branch of the NCI's Center for Cancer Research.
In conventional prostate cancer care, the current main method of diagnosis is systematic biopsy. It's a non-targeted method of taking tissue samples from across the prostate gland. But as the NCI team pointed out, this method can still potentially miss areas of cancer.
MRI-targeted biopsies could lead to better accuracy, Pinto's group said. In this approach, doctors merge previously taken MRI images of suspected cancer with real-time ultrasound technology, and are better able to detect more high-grade cancers than systematic biopsies.
In this study, the researchers investigated whether it would be better to replace systematic biopsy with MRI-targeted biopsies or to use both tests together.
The study included more than 2,100 men with prostate lesions that were visible on an MRI scan. All of the men underwent both MRI-targeted biopsies as well as traditional systematic biopsies.
Of these men, 1,312 were diagnosed with cancer and 404 underwent prostatectomy — the removal of the entire prostate.
Reporting in the March 5 issue of the New England Journal of Medicine, Pinto's team said that adding MRI-targeted biopsy to systematic biopsy led to 208 more cancer diagnoses, compared to using systematic biopsy alone.
The addition of MRI-targeted biopsy also led to 458 changes in diagnosis, alerting patients of a more aggressive cancer that might need more aggressive treatment, based on analysis of the biopsied tissue.
The two-method approach also provided more accurate diagnosis than MRI-targeted biopsies alone.
For example, among the men who underwent prostatectomy, systematic biopsy alone underdiagnosed about 40% of cancers, while MRI-targeted biopsy alone underdiagnosed about 30%. In contrast, combined biopsy underdiagnosed just 14.4% of the cancers, the researchers found.
And on the other hand, systematic biopsy alone underdiagnosed 16.8% of the most aggressive cancers, while MRI-targeted biopsy alone underdiagnosed 8.7% of the most aggressive cancers. But combining the two biopsy methods missed only 3.5% of the most aggressive cancers, Pinto's group said.
"Prostate cancer has been one of the only solid tumors diagnosed by performing systematic biopsies 'blind' to the cancer's location," Pinto noted. "For decades, this has led to the overdiagnosis and subsequent unnecessary treatment of non-lethal cancers, as well as to missing aggressive high-grade cancers and their opportunity for cure."
Two prostate cancer specialists said the study could be a game-changer in prostate cancer care.
"The study represents the culmination of much research and has now changed the trajectory of the evaluation of elevated [prostate-specific antigen] and prostate cancer diagnosis," said Dr. Manish Vira. He's vice chair of urologic research at the Arthur Smith Institute for Urology, in New Hyde Park, New York.
However, Vira cautioned that no method is perfect when it comes to accurate diagnosis, and that is "an important point to discuss with patients."
Dr. Art Rastinehad is vice chair of urology at Lenox Hill Hospital in New York City. He called the NCI team "pioneers" in advancing the science of prostate cancer diagnosis.
According to Rastinehad, the new study also "reinforces the recent update by the American Urological Association," in which the group recommended that an MRI precede every prostate biopsy.