Targeted biopsy using magnetic resonance/ultrasound fusion imaging increased the detection of high-risk prostate cancer by 30% and decreased the detection of low-risk prostate cancer by 17%, compared with standard biopsy, according to a report published online Jan. 27 in JAMA.

Researchers compared the two approaches in a prospective cohort study involving 1,003 men referred to the National Cancer Institute during a 7-year period for evaluation of suspected prostate cancer. All the study participants had an elevated PSA or abnormal findings on digital rectal exam plus a multiparametric MRI showing at least 1 lesion in the prostate, said Dr. M. Minhaj Siddiqui of the urologic oncology branch, National Cancer Institute, Bethesda, Md., and his associates.

All the patients underwent both standard extended-sextant ultrasound-guided biopsy and targeted magnetic resonance/ultrasound fusion biopsy at the same visit. The latter technique involves electronically superimposing multiparametric MR images in real time onto transrectal ultrasound images, which improves spatial localization and capture of location in three planes. The lesions were separately categorized as low-risk, intermediate-risk, or high-risk by highly experienced genitourinary radiologists.

The two image-guided biopsy techniques agreed on these classifications in 69% of cases and identified a similar number of cancers. However, targeted biopsy detected 173 high-risk tumors, compared with only 122 identified on standard biopsy, and targeted biopsy detected 213 low-risk tumors, compared with 258 identified on standard biopsy. In a subset of 170 cases, these biopsy results could be compared against pathology found at whole-gland prostatectomy. Targeted biopsy proved to be much more accurate than standard biopsy, with sensitivities of 77% and 53%, respectively, the investigators said (JAMA 2015 Jan. 27 [ doi:10.1001/jama.2014.17942 ]).

These findings show that targeted biopsy “could significantly change the distribution of risk in men newly diagnosed with prostate cancer toward diagnosis of more high-risk disease. Although these improvements in risk stratification could translate into substantial clinical benefits, it is important to recognize that this study is preliminary” and didn’t include clinical end points such as cancer recurrence or prostate cancer–specific mortality, Dr. Siddiqui and his associates said.