Gleason grade shift seen in retrospective analysis

Rochester, MN-Gleason scores are not what they used to be. Low-grade cancers, as described by Gleason scores 2 to 5, have virtually disappeared, while higher-grade cancers, particularly those identified as Gleason 6, have surged upward, according to a study performed at the Mayo Clinic, Rochester, MN.

The study by Dr. Sengupta, Michael L. Blute, MD, and colleagues was one of several presented at the 2005 AUA annual meeting showing a nationwide shift in biopsy-derived Gleason grades over time. The authors conjecture that there may be multiple factors driving the shift in grades.

"The other part is that we are picking up these cancers in a different way. In the past, a lot of low-grade cancers were picked up following transurethral resection of the prostate. Now very few cancers are being picked up on TURP. Most of them are PSA-detected cancers."

The Mayo Clinic group looked at data obtained from men who had undergone radical prostatectomy between 1989 and 2001. The size of the database allowed the team to examine the phenomenon of Gleason shift at a reasonably fine resolution. They found a significant increase in both primary and secondary Gleason grade 3 with a commensurate increase in Gleason 6 and Gleason 7 sums. There was a corresponding decrease in Gleason grade 2 and Gleason sums 4 and 5.

Delineation of grades

Dr. Sengupta pointed out that there was a better separation of secondary Gleason grades 2 through 5 in the contemporary scores than in the historical scores.

"Secondary grades 3 and 4 tended to overlap in the past, but today grades 2, 3, 4, and 5 are better separated. In other words, you are getting more prognostic information out of the Gleason system today than you were 10 years ago," he said.

This sharper delineation of grades may be responsible in part for improvements in prognosis seen during the past decade. Dr. Sengupta said that a patient diagnosed with grade 6 cancer today had a better biochemical recurrence-free survival at a similar post-op period than a patient diagnosed with grade 6 cancer 10 years ago.

These findings have implications for physicians and institutions endeavoring to determine the value of new procedures and technologies.

"There are new modalities being introduced, such as brachytherapy and other radiation treatments. The outcomes of these treatments are being compared to prostatectomy outcomes that may be 5 to 10 years old. These comparisons might not be valid unless the initial pathology is reviewed or compensation is made, such as introducing the year of treatment as a co-variable. That is not often done," Dr. Sengupta said.