The histological grading of prostate cancer has undergone many revisions requiring careful distinction between the terms Gleason grade, Gleason score and Grade Group.
The Gleason grade, originally described in 1974, describes the histologic pattern of gland arrangement 2. Gleason grade patterns are assigned from 1 to 5:
- 1: well formed glands (least aggressive)
- 5: lacking gland formation (most aggressive)
Most tumors demonstrate two histologic patterns and this is expressed as a Gleason score. The two most common grade patterns seen in a tumor are expressed together and summed. Gleason scores can be expressed as their individual components or as the total Gleason score, eg 3 + 4 = 7. The commonest pattern is noted first, hence Gleason score of 4 + 3 = 7 is more aggressive than Gleason score of 3 + 4 = 7.
One would expect Gleason scores of between 2 and 10, however, Gleason scores less than 6 are not assigned in practice. This leads to patient concern as the lowest possible Gleason score is "6 out of 10". This prompted further revision of prostate cancer grading.
Grade Group stratification was introduced by the International Society of Urological Pathology (ISUP)3 and has been adopted by the American Joint Committee on Cancer (AJCC). The Gleason score system is compressed into 5 Grade Groups as per Table 1.
The new Grade Group better reflects prostate cancer biology, with 5-year biochemical risk-free survival after radical prostatectomy of 3:
- Grade Group 1: 96%
- Grade Group 2: 88%
- Grade Group 3: 63%
- Grade Group 4: 48%
- Grade Group 5: 26%
History and etymology
Named after Donald Gleason, American (US) pathologist (1920-2008).
- 1. Cramer SD. Prostate Cancer. Chelsea House Pub. (2007) ISBN:0791089355. Read it at Google Books - Find it at Amazon
- 2. Gleason DF, Mellinger GT. Prediction of prognosis for prostatic adenocarcinoma by combined histological grading and clinical staging. (1974) The Journal of urology. 111 (1): 58-64. Pubmed
- 3. Epstein JI, Egevad L, Amin MB, Delahunt B, Srigley JR, Humphrey PA. The 2014 International Society of Urological Pathology (ISUP) Consensus Conference on Gleason Grading of Prostatic Carcinoma: Definition of Grading Patterns and Proposal for a New Grading System. (2016) The American journal of surgical pathology. 40 (2): 244-52. doi:10.1097/PAS.0000000000000530 - Pubmed
Related Radiopaedia articles
- prostate tumors
- infections of the prostate
- benign prostatic hypertrophy
- cystic lesions of the prostate
- prostatic calcification
- prostatic infarction