A population-based study recently validated the five-tiered Gleason Grade Grouping system for predicting mortality among patients with prostate cancer, published in European Urology.
Clinicians have used the Gleason Grade Grouping system to predict prostate cancer-specific outcomes since it was initially introduced in the 1960s. What was once a nine-patterned system has been condensed into a five-grade system for predicting disease risk. The goal of this new five-tiered system, which had yet to be validated, is to improve the accuracy of prostate cancer mortality-risk classification.
Researchers led by Grace Lu-Yao, PhD, MPH, Associate Director for Population Science, Sidney Kimmel Cancer Center, Thomas Jefferson University (Philadelphia, PA), utilized the Surveillance, Epidemiology, and End Results (SEER) database to evaluate 331,320 men diagnosed with prostate cancer between 2006 and 2012 who had primary and secondary Gleason patterns recorded. Fine and Gray proportional hazards model was used to calculate sub-distributions and cumulative incidence to quantify the risk of prostate cancer-specific mortality.
Median follow-up among sampled patients was 38 months. A majority of patients had received either radical prostatectomy (36.4%) or radiation therapy (32.6%) as primary treatment.
Researchers found that the risk of mortality approximately doubled with each Gleason Grade Grouping increase. Patients who underwent radical prostatectomy and used Gleason Grade Grouping-1 (Gleason score ≤ 6) as the reference group had an adjusted hazard ratio for mortality of 1.13 for Grouping-2; 1.87 for Grouping-3; 5.03 for Grouping-4; and 10.92 for Grouping-5. A similar doubling pattern was observed regardless of the type of primary cancer treatment received or clinical stage diagnosed.
Researchers deemed the results demonstrative of the accuracy of the new five-tiered Gleason Grade Grouping system. “Our study, based on broad representation of racially diversified populations, is the first one to demonstrate that this new [five]-tiered Gleason Grade Grouping system is a powerful predictor of prostate cancer–specific mortality across different cancer stages and cancer therapies and can serve as the cornerstone of risk stratification to guide treatment decisions,” said Dr Lu-Yao.
