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Five-tiered Gleason grouping system predicts prostate cancer mortality
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Researchers successfully validated the five-tiered Gleason Grade Grouping system for predicting mortality among men with prostate cancer, according to results of a population-based study.
“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,” Grace Lu-Yao, PhD, MPH, associate director for population science at Sidney Kimmel Cancer Center of Thomas Jefferson University, told HemOnc Today.
Clinicians have relied on the use of the Gleason Grade Grouping system (GGG) since it was first introduced. It was once a nine-patterned system that has been consolidated into five grades in a teaching diagram.
“It is well known that the structure of the cell is a powerful predictor of the aggressiveness of prostate cancer,” Lu-Yao said. “The goal of the newly proposed five-tiered GGG is to improve the accuracy of the disease risk classification.”
It was still unknown if the new GGG accurately predicted prostate cancer mortality risk. Therefore, Lu-Yao and colleagues extracted data from the SEER database and evaluated 331,320 men diagnosed with prostate cancer between 2006 and 2012 and who had primary and secondary Gleason patterns recorded.
The researchers used Fine and Gray’s proportional hazards model to calculate sub-distributions and cumulative incidence to quantify the risk for prostate cancer mortality. GGG1 — indicating a Gleason score lower than 6 — was used as the reference group.
The median follow-up was 38 months. The majority of patients had received radical prostatectomy (36.4%) or radiation therapy (32.6%) as primary treatment.
Using the proposed five-tiered GGGs, the study cohort was reclassified into the following: 43.3% as GGG1, 29.5% as GGG2, 11.7% as GGG3, 8.1% as GGG4 and 7.5% as GGG5.
When using the GGG1 group as reference, the prostate cancer–specific mortality HR increased with each group, regardless of the type of primary cancer treatment and clinical stage.
Among men who received previous radical prostatectomy, the adjusted HRs were 1.13 (95% CI, 0.83-1.54 for GGG2; 1.87 (95% CI, 1.33-2.65) for GGG3; 5.03 (95% CI, 3.59-7.06) for GGG4; and 10.92 (95% CI, 8.03-14.84) for GGG5. Thus, for each GGG increase the HR doubled and appeared significantly different than that of the other groups.
Researchers noted these findings persisted among patients who underwent radiotherapy and other treatments, as well as by clinical stages.
“In order to provide optimal care for patients with prostate cancer and make the best treatment decisions, it is critical to consider the aggressiveness of the disease and life expectancy,” Lu-Yao said. “For patients with a short life expectancy and nonaggressive disease, conservative management such as active surveillance may be the best treatment choice. On the other hand, for patients with a long-life expectancy and aggressive disease, radical prostatectomy or radiotherapy may be potential options.” – by Melinda Stevens
For more information:
Grace L. Lu-Yao, PhD, MPH, can be reached at Sidney Kimmel Medical College, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA 19107; email: grace.luyao@jefferson.edu.
Disclosure: Lu-Yao reports no relevant financial disclosures. One study researcher reports employment with Johnson & Johnson.
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