Hebert Alberto Vargas, M.D., from the Memorial Sloan-Kettering Cancer Center in New York City, and colleagues analyzed data from 388 consecutive men (mean age, 60.6 years) with clinically low-risk prostate cancer (initial biopsy Gleason score ≤6, prostate specific antigen <10 ng/mL, clinical stage T2a or less) who underwent endorectal MRI before confirmatory biopsy. Tumor visibility on endorectal MRI was scored by three radiologists independently using a five-point scale.

The researchers found that confirmatory biopsy upgraded the Gleason score in 79 of 388 (20 percent) patients. There was a high negative predictive value (0.96 to 1.0) and specificity (0.95 to 1.0) for MRI scores of ≤2 for upgrading on confirmatory biopsy; an MRI score of 5 was also highly sensitive (0.87 to 0.98). Patients with higher MRI scores were more likely to have disease upgraded on confirmatory biopsy (odds ratio, 2.16 to 3.97). For prediction of low-risk and very-low-risk prostate cancer (Gleason score of 6, <3 positive cores, <50 percent involvement in all cores), MRI performed similarly.

"The fact that clear tumor visualization on MRI was predictive of upgrading on confirmatory prostate biopsy suggests that prostate MRI may contribute to the complex process of assessing patient eligibility for active surveillance," the authors write.

Abstract
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