Biopsy Gleason Scores Often Wrong

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In 29% of cases, high biopsy scores are downgraded to 7 or less after radical surgery, study finds.

Nearly one third of prostate tumors judged to have high Gleason scores at biopsy may be intermediate-risk cancers, a finding that could have implications for treatment decisions, according to Brazilian researchers.

Katia Ramos Moreira Leite, MD, PhD, of the Universidade de São Paulo, and collaborators reviewed data on 464 men (mean age 61.6 years; mean PSA level 7.1 ng/mL) whose Gleason scores on extended prostate biopsy were compared with their scores following radical prostatectomy. The pathologic stage was pT2 in 73.9% of patients and pT3 in 26.1%.

Biopsy and radical prostatectomy Gleason scores agreed in nearly 57% of cases, the authors reported in the International Journal of Radiation Oncology Biology Physics (2008; published online ahead of print). Biopsy findings underestimated Gleason scores in 29% of cases and overestimated scores in 14%. Of 464 men, 106 (22.8%) had tumors with a high Gleason score (8 or higher) based on biopsy.

After radical prostatectomy, the Gleason score in 29.2% of patients was actually 7 or lower. Compared with other tumors, those with overestimated Gleason scores were significantly smaller. The total percentage of tumor was the only independent factor in the overestimation of Gleason score. Tumors found in fewer than 33% of cores had a 5.6 times greater risk of being overestimated.

When Dr. Leite's group compared patients whose high Gleason score was confirmed with those whose score was overestimated, they found no significant difference in patient age or PSA levels, and the number of cores taken in each biopsy section was similar. With respect to pathologic stage, 71% of patients whose Gleason score was overestimated had pT2 disease compared with only 40% of patients whose high Gleason score was confirmed.

The investigators concluded that “Gleason upgrading in extended prostate biopsy is a relatively common event that should be remembered by pathologists, urologists, oncologists, and radiotherapists when choosing the best therapy to treat prostate cancer. Tumor extension in biopsies can be a helpful parameter, with a high probability of smaller tumors being of intermediate Gleason grade and organ-confined.”

In those cases, the authors added, brachytherapy could be an option, along with pelvic lymph-node dissection or radiation. Associated anti-androgen therapy could be avoided, preventing severe adverse effects, they noted.

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