乌鸦传媒

MRI-guided prostate biopsy detected almost 50% more clinically significant prostate cancers as compared with standard ultrasound-guided biopsy, an international group of investigators reported.

With multiparametric MRI, 38% of men with suspected prostate cancer had clinically significant tumors at targeted biopsy, as compared with 26% of men randomized to conventional transrectal ultrasound (TRUS)-guided biopsies. An adjusted data analysis yielded a 13% absolute reduction in the diagnosis of clinically insignificant tumors with MRI assessment and subsequent MRI-targeted biopsy (P<0.001), reported Veeru Kasivisvanathan, MD, of University College London, and colleagues.

While the authors did not call for a change in practice on the basis of their findings, they did address the issue in their concluding remarks.

"We acknowledge that a change in the standard of care for prostate cancer diagnosis would entail changes in the healthcare systems to accommodate appropriate MRI capacity and to meet the training needs of radiologists and urologists," they wrote in the . "From a health economics perspective, the cost savings with MRI, with or without targeted biopsy, over standard transrectal ultrasonography-guided biopsy may emerge from the earlier detection of clinically significant cancers, fewer cancers of insignificant cancer diagnosed, and fewer repeat biopsies."

"Reports from other studies and in different contexts suggest that this pathway may be cost-effective in the long term."

The authors also acknowledged that the study was conducted at centers that perform a large volume of MRI-guided prostate evaluations and biopsies, and that all the participating radiologists had substantial experience with MRI-guided prostate procedures.

The results should come as no surprise to prostate cancer specialists and radiologists who specialize in prostate imaging, said Eric Klein, MD, of the Cleveland Clinic.

"It confirmed what everybody thought it would confirm: that MRI makes biopsy more accurate," Klein told 乌鸦传媒. "It reduces the likelihood of finding a cancer that we don't want to know about -- low-grade, Gleason 6 cancers -- and increases the likelihood of finding something that is biologically significant and needs treatment."

However, technology for diagnosing prostate cancer and imaging the prostate continues to evolve, and better diagnostic options may be yet to come, added Klein, who was not involved in the study. New-generation ultrasound machines offer much higher-resolution imaging as compared with machines currently in widespread use in clinical practice. Additionally, new diagnostic tests, including new approaches to measuring PSA, have shown promise for improving diagnostic accuracy, including tests designed for use with MRI.

TRUS-guided prostate biopsy to obtain 10 to 12 core samples results in underdetection of high-grade prostate cancers and overdetection of low-grade (clinically insignificant) prostate cancers that are unlikely to benefit from treatment, Kasivisvanathan's group noted. Multiparametric MRI-targeted prostate biopsy has demonstrated potential to reduce much of the under- and overdiagnosis and associated treatment issues. However, most of the data came from single-center studies.

Investigators in the multicenter sought to determine whether multiparametric MRI, followed by targeted biopsy of abnormal-appearing lesions, is noninferior to TRUS-guided biopsy with 10 to 12 cores for detection of clinically significant prostate cancer (Gleason score ≥7). In the MRI group, biopsy was limited to patients who had prostate lesions with scores of 3-5 on the scoring system (equivocal to highly likely for presence of cancer).

Clinicians at 25 centers in 11 countries enrolled and randomized 500 patients to the two biopsy strategies. Men in the two arms of the trial did not differ significantly with respect to age (64), baseline PSA level (6.5-6.75 ng/mL), family history of prostate cancer (16%-19%), or proportion with abnormal digital rectal examinations (14%-15%).

The results showed an absolute increase of 12% in the diagnosis of clinically significant prostate cancer with the MRI-based strategy (95% CI 4% to 20%, P=0.005). The difference not only met the prespecified boundary for noninferiority (-5% vs TRUS-guided biopsy) but demonstrated superiority for MRI, with or without targeted biopsy.

Significantly fewer men in the MRI group had clinically insignificant prostate cancers as compared with the TRUS-guided strategy (9% versus 22%, 95% CI -19% to -7%, P<0.001).

A higher proportion of biopsy cores proved to be positive for cancer with MRI (44% versus 18%), and the maximum cancer core length among men with cancer was 7.8 mm in the MRI group and 6.5 mm in the TRUS group (P=0.053).

The authors of an cautioned that the results represent intermediate outcomes, whereas the impact of MRI-guided biopsy on morbidity and mortality will require evaluation of many more patients followed for many years.

"Nevertheless, the findings suggest that multiparametric MRI may have a place in decisions about prostate biopsy," wrote Michael J. Barry, MD, of Massachusetts General Hospital in Boston, and Andrew B. Rosenkrantz, MD, of NYU Langone Medical Center in New York City. "Because of the major implications for wider use of multiparametric MRI in evaluating men with elevated PSA levels -- including the need for additional MRI equipment and personnel and the effect on total costs -- these findings should be replicated and extended."