A new grading system based on Gleason scores can help doctors better estimate prostate cancer aggressiveness, a new European validation study confirms.
The system is user friendly, clinically relevant and reproducible, researchers write in Prostate Cancer and Prostatic Diseases, online January 10.
"The new grading system has obvious benefits: 1) more accurate grade stratification than the old Gleason system; 2) simpler grading system of 1 to 5 as opposed to multiple possible scores depending on various Gleason pattern combinations; and 3) the lowest grade with a score of 1 may potentially reduce overtreatment of insignificant prostate cancer," said senior author Dr. Shahrokh Shariat from the Medical University of Vienna, Austria.
"While the new grading system was accepted in 2016 by the World Health Organization (WHO), it was not validated in large multicentric datasets and not specifically in European patients. These premises are necessary before widespread adaptation of this tool to risk stratify prostate cancer patients accurately," he told Reuters Health by email.
Dr. Shariat and his colleagues validated the independent prognostic value of the new grade groups on biopsy and radical prostatectomy (RP) specimens from European men with prostate cancer.
Analyzing data from more than 27,000 patients treated with RP at seven European medical centers, they assessed the prognostic success of the system based on Gleason scores 3+3, 3+4, 4+3, 8 and 9-10. The median follow-up was 29 months.
The estimated four-year biochemical-recurrence-free survival (bRFS) for biopsy grade groups 1 through 5 were 91.3%, 81.6%, 69.8%, 60.3% and 44.4%, respectively; for RP grade groups 1 through 5, it was 96.1%, 86.7%, 67.0%, 63.1% and 41.0%, respectively.
All other groups, based on both biopsy and RP specimen, were independently associated with lower bRFS, compared with grade group 1 (p<0 .01="" 3="" 4="" adjusted="" all="" and="" between="" comparisons="" differences="" except="" for="" grade="" groups.="" groups="" on="" p="" pairwise="" rp="" showed="" significant="" specimen="">
"We hope that the implementation of this new grading system will decrease overtreatment while it helps patients with aggressive disease get multimodal therapy," Dr. Shariat said.
"As the new grading system is simpler and more accurately reflects prostate cancer biology, we recommend its use in conjunction with the older Gleason grading until it becomes widely accepted and practiced."
Dr. Soroush Rais-Bahrami, a urologist at the University of Alabama at Birmingham, who was not involved in the study, told Reuters Health by email, "The large number of men evaluated in this study, analyzed from 7 different institutions, provides a real-world validation of this new classification system."
"Along with other clinical factors, the new prostate cancer grading system helps clinicians categorize patients into low, intermediate, or high risk for disease recurrence. In this way, clinicians can better guide patients in shared decision making," he said.
Pathologist Dr. Jennifer B. Gordetsky, also at the University of Alabama at Birmingham, said, "The findings from this study are excellent and support other similar multi-institutional studies performed in the United States. The study further validates the use of the new prostate cancer grading system as well as the longtime utilized Gleason grading system."
"Although the current study is excellent, the authors evaluated prostate specimens dating back to 2005," she told Reuters Health by email. "The Gleason grading system has been modified twice during this time and may confound some of their findings."
Dr. James Mohler of Roswell Park Cancer Institute in Buffalo, New York, noted in an email to Reuters Health that the 2017 National Comprehensive Cancer Network (NCCN) guidelines include Gleason grade groups, which should make treatment decision making easier for patients.
"The real benefit is to patients who have had trouble understanding Gleason scores," Dr. Mohler noted