The 2014 International Society of Urological Pathology (ISUP) Consensus Conference on Gleason Grading of Prostatic Carcinoma
- Study type
- Clinical guideline
- Study name
- ISUP 2014
- Design
- Expert consensus conference (November 2014) to update prostate cancer grading, last revised in 2005
- Sample size
- 65 prostate cancer pathologists and 17 clinicians (urologists, radiation oncologists and medical oncologists) from 19 countries
- Source
- American Journal of Surgical Pathology · 2016
In plain words
Pathologists set the "grade" of prostate cancer by looking at a sample under the microscope. Until then, the Gleason score ran from 2 to 10, but in practice the lowest score given was 6, which made patients with a score of 6 think their cancer was aggressive. At this international conference, a simpler system with 5 "grade groups" (1 to 5) was adopted, in which the lowest-risk group is group 1. This system helps patients and doctors understand the risk of the cancer better and may help avoid overtreating slow-growing cancers.
Key points
Key guideline recommendations
- Conference consensus
Cribriform glands should be assigned Gleason pattern 4 regardless of morphology.
- Conference consensus
Glomeruloid glands should be assigned Gleason pattern 4 regardless of morphology.
- Conference consensus
Mucinous carcinoma of the prostate should be graded on its underlying growth pattern rather than all cases being graded as pattern 4.
- Conference consensus
Intraductal carcinoma of the prostate without invasive carcinoma should not be assigned a Gleason grade, and a comment should be added on its constant association with invasive prostate cancer.
- Conference consensus
To diagnose Gleason pattern 4, the pattern should be seen with a 10× objective lens; occasional seemingly poorly formed or fused glands among well-formed glands are not enough to diagnose pattern 4; in borderline cases between patterns 3 and 4, and in the presence of crush artefact, the lower grade should be preferred.
- Conference consensus
Small solid cylinders, solid medium to large nests with rosette-like spaces, and unequivocal comedonecrosis (even if focal) indicate Gleason pattern 5. The term hypernephroid cancer should not be used, and branched glands are allowed in pattern 3.
- 90% consensus
The new grading system with grade groups 1 to 5 was adopted and will be used alongside the Gleason system for the foreseeable future.
Study population
Conference participants: 65 prostate cancer pathologists together with 17 clinicians, including urologists, radiation oncologists and medical oncologists, from 19 countries. The new grading system was validated in a multicentre study of more than 20,000 radical prostatectomy specimens, more than 16,000 needle biopsy specimens and more than 5,000 biopsies followed by radiotherapy.
Endpoints
This study is not a clinical trial and has no treatment endpoint. The aim of the conference was to update the definitions of the Gleason patterns and to consider a proposal for a new grading system (grade groups 1 to 5). The criterion for adopting the new system was the level of consensus among participants.
Safety and side effects
This study does not concern treatment adverse effects, and no safety data are reported in the abstract.
Clinical significance and place in guidelines
According to the abstract, grade groups 1 to 5 are used alongside the Gleason score (e.g. Gleason 3+3=6 corresponds to grade group 1), and the World Health Organization has also adopted them for the 2016 edition of its book on tumours of the urinary system and male genital organs. This system can clarify the distinction between 3+4 and 4+3 and, by labelling the lowest-risk cancers as grade 1, can reduce overtreatment. The current status of this system in other clinical guidelines should be checked separately.
Limitations
This document is the result of expert consensus and is not a clinical trial. The abstract does not specify the level of evidence for the recommendations and does not report detailed validation results (such as survival rates). The participants themselves also acknowledged shortcomings of the Gleason system. Full details should be checked in the full text.
This summary was prepared by the editorial team from the published paper; the original paper is the final reference. Read the original abstract on PubMed.