Among men undergoing biopsy for suspected prostate cancer, targeted magnetic resonance (MR)/ultrasound fusion–guided biopsy was associated with an increased rate of detection of high-risk prostate cancer and a decreased rate of detection of low-risk prostate cancer than was standard extended-sextant ultrasound-guided biopsy. The results from a prospective cohort study of 1,003 men undergoing both targeted and standard biopsy concurrently from 2007 through 2014 at the National Cancer Institute were published in JAMA.
“Patients were referred for an elevated level of prostate-specific antigen (PSA) or abnormal digital rectal examination results, often with prior negative biopsy results. Risk categorization was compared among targeted and standard biopsy and, when available, whole-gland pathology after prostatectomy as the ‘gold standard,’” Peter A. Pinto, MD, and M. Minhaj Siddiqui, MD, of the National Cancer Institute and colleagues reported.
Multiparametric prostate MR imaging “allows for imaging-based identification of prostate cancer, which may improve diagnostic accuracy for high-risk tumors,” the authors explained. These images are electronically superimposed in real time on transrectal ultrasound images by targeted (MR)/ultrasound fusion–guided biopsy platforms. “Numerous targeted biopsy platforms exist and are capable of performing biopsies of suspicious prostate regions on multiparametric prostate MR imaging,” the authors noted.
“Targeted MR/ultrasound fusion–guided biopsy diagnosed 461 prostate cancer cases, and standard biopsy diagnosed 469 cases. There was exact agreement between targeted and standard biopsy in 690 men (69%) undergoing biopsy,” the researchers reported. Targeted biopsy, however, diagnosed 30% more high-risk cancers than standard biopsy (173 vs 122 cases, P < .001) and 17% fewer low-risk cancers (213 vs 258 cases, P < .001).
Combining standard biopsy cores with the targeted approach led to an additional 103 cases (22%), but mostly low-risk prostate cancer was diagnosed (83% low risk, 12% intermediate risk, and 5% high risk). “This equated to a number needed to biopsy with standard biopsy in addition to targeted biopsy of 200 men to diagnose 1 additional high-risk cancer,” the researchers stated. “Furthermore, for every additional case of high-risk cancer diagnosed, 17 additional cases of low-risk cancer would be diagnosed.”
Targeted biopsy was also better at predicting whole-gland pathology at prostatectomy than standard biopsy or the two approaches combined. The sensitivity of targeted biopsy was 77% vs 53% for standard biopsy, and the specificities were similar, 68% vs 66%.
Study Implications
“This study demonstrated that targeted biopsy could significantly change the distribution of risk in men newly diagnosed with prostate cancer toward diagnosis of more high-risk disease,” the authors concluded. “Although these improvements in risk stratification could translate into substantial clinical benefits, it is important to recognize that this study is preliminary with regard to clinical endpoints such as recurrence of disease and prostate cancer–specific mortality. These findings provide a strong rationale for the conduct of randomized clinical trials to determine the effect of targeted biopsy on clinical outcomes.”
In an accompanying editorial, Lawrence H. Schwartz, MD, of Columbia University College of Physicians and Surgeons, New York, and JAMA Associate Editor Ethan Basch, MD, of the University of North Carolina, Chapel Hill, noted that “any new technology that improves the ability of biopsy to distinguish between men with lower- and higher-risk cancers has the potential to influence clinical decisions and improve patient outcomes.” The editorialists cautioned, however, that “a new test should not be widely adopted in the absence of direct evidence showing benefits on quality of life, life expectancy, or ideally both.” ■
Siddiqui MM, et al: JAMA 313:390-397, 2015.
Schwartz LH, Basch E: JAMA 313:367-368, 2015.
