How Are Gleason Scores Categorized in the Current Literature: An Analysis and Comparison of Articles Published in 2016-2017

A new prostate cancer grading system was proposed in 2013 and endorsed by major journals and societies in 2014, in part because of anecdotal evidence that Gleason scores (GSs) were incorrectly combined in the literature.

To examine how published studies categorized GSs in current practice.

A PubMed search was conducted on articles published in 2016-2017 using the search terms "Gleason" and "prostate". This literature review included 1576 articles after exclusions.

(1) Separating GS 7: pathology journals were more likely than non-pathology journals to grade GS 7 separately (56.9% vs 40.0%, p<0.05). Articles co-authored by a pathologist separated GS 7 more than those without a pathologist (53.2% vs 32.9%, p<0.001). North American and European studies separated GS 7 more than Asian studies (47.6% and 44.1% vs 24.1%, p<0.001). Clinical articles separated GS 7 more than research articles (43.7% vs 32.9%, p<0.001). (2) Separating GS 8 from GS 9-10: pathology journals separated GS 8 from GS 9-10 more than non-pathology journals (55.2% vs 34.4%, p=0.001). Articles co-authored by a pathologist separated GS 8 from GS 9-10 more often than those without a pathologist (44.9% vs 29.5%, p<0.001). (3) Using grade groups as "ideal" with all other groupings "non-ideal": pathology journals used ideal more than non-pathology journals (32.2% vs 15.9%, p<0.001). Ideal grouping is more likely in articles co-authored by a pathologist than in those without a pathologist (20.6% vs 11.0%, p<0.001). North American and European studies used ideal grouping more than Asian studies (17.6% and 14.0% vs 9.1%, p<0.05). (4) Arranging groupings in decreasing order from ideal to non-ideal: pathology journals were closer to ideal than non-pathology journals (p=0.002). Articles co-authored by a pathologist were classified closer to ideal than those without a pathologist (p<0.001). North American (p<0.001) and European (p=0.02) studies were closer to ideal than Asian studies.

There is still wide variation in how GSs are grouped world-wide. Only a minority of published articles group GSs accurately.

In this report, we looked at how GSs were grouped world-wide. We found that only a minority of published articles on prostate cancer were grouping GSs accurately, which could lead to inaccurate results and affect patient care with different prostate cancer grades. Our study calls for more widespread adoption of the new prostate cancer grading system composed of five grade groups to minimize incorrect grouping for future studies.