A consensus panel of experts has proposed a new and simpler prostate cancer (PCa) grading system that could help clinicians give patients a better understanding of their prognosis.
The system, initially proposed by Jonathan I. Epstein, MD, professor of pathology, urology, and oncology at Johns Hopkins Medical Institutions in Baltimore, MD, and supported by the International Society of Urological Pathology (ISUP), is based largely on the 1967 to 1973 Gleason scoring system, but more accurately reflects PCa biology than the Gleason system. It incorporates the latest understanding of the pathologic and clinical aspects of PCa.
The new grading system, first described in BJU International in 2013 and recently verified in a large multi-institutional study described in the upcoming March issue of European Urology, consists of 5 “grade groups,” with grade group 1 indicating the most favorable prognosis and grade group 5 the least favorable.1,2 In the Gleason scoring system, 25 grading combinations are possible.
In an interview with Cancer Therapy Advisor, Dr Epstein said the proposed system distills pathologic findings into the key differences in prognosis “that can be intuitive to both patients and clinicians,” he said.
“Clinicians will be forced to look at the grades appropriately in terms of different prognoses,” Dr Epstein said.
The original Gleason system used PCa-related death as an outcome, whereas the new system uses biochemical recurrence as an outcome, although recent studies have verified that the new system also predicts death due to PCa.
A noteworthy aspect of new grading system is the distinction it makes between Gleason score 3 + 4 and 4 + 3 cancers, which often are simply called Gleason score 7 disease in discussions with patients. Dr Epstein emphasized that Gleason 3 + 4 tumors are associated with substantially better prognoses than Gleason 4 + 3 tumors. The new grading system separates these cancers into grade groups 2 and 3, respectively.
This distinction could affect patient decisions whether to be placed on active surveillance if their doctors recommend it. Patients may feel more comfortable with this approach if they are told their cancer is a grade 2 out of 5 instead of a Gleason 7 out of 10, Dr Epstein said.
Another important feature of the new system is the placement of Gleason score 6 cancers into grade group 1. Dr Epstein pointed out that patients with Gleason score 6 disease often believe their prognosis is worse than it is because Gleason score 6 is half way along the Gleason scoring scale of 2 to 10, when, in fact, a Gleason score 6 tumor is the lowest-grade cancer currently assigned with an excellent prognosis. The new system reflects this.
The new grading system has been in use at Johns Hopkins since 2013, with biopsy reports including both Gleason scores and grade groups, and clinicians at the institution have embraced it, Dr Epstein said. “It helps them to explain to patients in simple terms the relative prognosis of their tumors,” he said.