Prostate cancers diagnosed at repeat biopsy are as likely to be high grade as those found at initial biopsy, researchers reported in The Journal of Urology (2008;180:1325-1329).

The finding, by Nelly Tan, M.D., and her colleagues at Cleveland Clinic in Ohio, comes from a review of 905 newly diagnosed prostate cancer cases. In 57% of cases, prostate cancer was diagnosed on initial biopsy. In 23% and 21% of cases, cancer was diagnosed in patients with one and two or more previously negative biopsies, respectively. Prostate cancers diagnosed on initial biopsy had higher volume. A significant number of high-grade cancers were found in patients who had three or more biopsies.

Initial prostate biopsies showed a higher number of positive cores and cores with a higher percentage of cancer, but the largest percentage (14%) of Gleason 8 or greater cancer was found in patients with two or more negative previous biopsies.

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After adjusting for PSA, digital rectal examination (DRE) findings, age, and biopsy schema, the number of previous biopsies was an independent predictor of the number and percent of positive cores, maximum prostate cancer involved in a core, and bilaterality. Only PSA, DRE, and age, but not number of previous biopsies, independently predicted Gleason sum, according to investigators.

Study findings underscore the importance of repeat biopsy in patients with increased or increasing PSA following negative previous biopsies, the authors concluded.