Gleason Pattern 5 is a Possible Pathologic Predictor for Biochemical Recurrence after Laparoscopic Radical Prostatectomy

Prognostic significance of tertiary Gleason pattern in the contemporary era of Gleason grade grouping: A narrative review

Since the Gleason score was developed in 1966 as a histological classification for prostate cancer, it has been widely used in clinical practice and has evolved over time. The concept of a "tertiary Gleason pattern" (also known as a minor Gleason pattern) was first proposed in 2000, and has been used in clinical practice since the 2005 International Society of Urological Pathology conference. The prognostic significance of a tertiary Gleason pattern has been widely validated in various settings of prostate cancer, whereas its definition has yet to be fully established. Currently, a provisional definition of tertiary Gleason pattern is "<5% Gleason pattern 4 or 5 in radical prostatectomy specimens." In contrast, "Gleason grade grouping" was proposed in 2013 and came into use in clinical practice in 2016 according to the 2014 International Society of Urological Pathology conference. Although the prognostic significance of Gleason grade grouping has already been widely confirmed, it does not incorporate the concept of tertiary Gleason pattern. Recently, the 2019 International Society of Urological Pathology conference discussed how to handle tertiary Gleason pattern in the current Gleason scoring system, but no consensus was reached on the issue. This review summarizes the evidence on the prognostic significance of tertiary Gleason pattern and discusses how to deal with it in the context of the contemporary Gleason grade grouping. It also refers to reporting of the percentage of Gleason patterns 4 and 5, as well as quantitative Gleason score models incorporating tertiary Gleason pattern.

Gleason grade 5 prostate cancer: sub-patterns and prognosis

Since the conception of the Gleason grading system, several modifications have been made, including the definition of Gleason pattern 5 (GP5) and its reporting in biopsies and prostatectomy specimens. This includes the addition of a few GP5 sub-patterns over time such as single file, solid cylinders and pseudorosetting. Comedonecrosis was also adopted as a GP5 pattern, but in 2014 the International Society of Urological Pathology (ISUP) excluded intraductal carcinoma with comedonecrosis from the GP5 sub-patterns, although the vast majority of cases with comedonecrosis actually represent intraductal carcinoma. The 2019 conference on prostate cancer grading re-adopted comedonecrosis as GP5, also if found in intraductal carcinoma. It is well-established that presence of GP5 conveys an unfavourable prognosis for the patient with regards to risk of lymph node and distant metastasis as well as death of disease. However, there is a paucity of data on the prognostic impact of individual GP5 sub-patterns. In biopsies the frequency of diagnosis of GP5 is about 1-5% in most published series and the most common GP5 sub-pattern is single files and single cells. In an institutional biopsy review study we noted an increase in GP5 diagnosis over time which could not be attributed to the adoption of new GP5 sub-patterns or to overdiagnosis, but might be associated with changing biopsy indications. Further studies on the prognostic impact of GP5 sub-patterns and their molecular genetic profile are indicated.