Approximately 95% of all cancers that develop in the prostate are adenocarcinomas.32 The majority are acinar adenocarcinomas, with variants of usual acinar adenocarcinoma including:33
- colloid (mucinous)
- signet ring
Non-acinar carcinoma variants account for about 5% - 10% of primary prostate cancers and include:33
- sarcomatoid carcinoma
- ductal adenocarcinoma
- urothelial carcinoma
- squamous and adeno squamous carcinoma
- basal cell carcinoma
- clear cell adenocarcinoma
- microcystic adenocarcinoma
- PIN-like adenocarcinoma
- large-cell neuroendocrine carcinoma
- pleomorphic giant cell adenocarcinoma
- prostatic intraepithelial neoplasia (PIN).
Assessment of disease volume and grade of the cancer is important for determining an appropriate treatment plan. Following examination of tissue samples obtained via prostate biopsy, a histological grade is assigned to assist in predicting pathologic grade and prognosis.
The most common histological grading system for prostate cancer is the Gleason grading system, which was developed in 1966, and modified following a 2005 consensus conference of international experts in urological pathology.34 The modifications are in response to advances in prostate cancer diagnosis including prostate specific antigen testing, prostate biopsy techniques with greater sampling, immunohistochemistry for basal cells that changed the classification of prostate cancer and new prostate cancer variants.34 The Gleason score is incorporated into a number of the tools (Partin tables or Kattan nomograms) clinicians use to predict outcomes, including the pathological stage or prognosis.35
Biopsy core specimens are evaluated under a microscope and assigned a score based on architectural patterns. Sections of tumour are graded from 1 (low grade) to 5 (high grade) and the two predominant patterns from each tumour are added to give a score ranging from 2 to 10. Historically, tumours with a score of less than 7 tended to have a good prognosis, while those with a score of 7 and above tend to have a poorer prognosis.36
In the modified Gleason grading system:
- a Gleason score of needle biopsy specimens less than 4 are rarely made35
- Gleason score 6, margin negative cancer is highly curable35
- the prognosis of a tumour with Gleason Score of 7 varies considerable depending of the predominance of Gleason pattern 4.37
Prostate cancer is most commonly staged using the tumour, nodes, metastases (TNM) classification system.36 The prostate cancer is then classified as localised, locally advanced, or metastatic disease.36
Prostate Cancer Staging. 7th Edition(PDF, 1.01MB)38 American Joint Committee on Cancer, 2009.
A number of tumour characteristics are used to predict cancer outcomes:39, 40
- PSA level
- PSA changes such as velocity and doubling time
- Gleason score
- tumour stage.
Based on these characteristics, risk strata have been defined and may be used to guide treatment recommendations. Risk groups include: 31, 40
- very low-risk
- locally advanced.
Access Localised prostate cancer: a guide for men and their families(PDF, 1.91MB)26 and discuss how you could use this resource to provide information to a man newly diagnosed about staging and grading of prostate cancer.
Access the Guidelines on Prostate Cancer (2015),31 and:
- Distinguish the features of low, intermediate and high risk prostate cancer
- Discuss the implications of each of these above classifications for a man's cancer journey.
M ☑ F ☐
1-2. Sections show cores of benign prostatic tissue. There is no high-grade PIN* or invasive malignancy.
3. Sections show acinar adenocarcinoma, Gleason score 3+4 (10%) = 7, involving 3mm of the core biopsy. No perineural permeation or extraprostatic extension is identified.
4-8. Sections show cores of benign prostatic tissue. There is no high-grade PIN or invasive malignancy.1-8. TRUS Biopsies of prostate, sites as specified above - Acinar adenocarcinoma, Gleason score 3+4=7, involving one of eight biopsies (right apex); no perineural permeation or extraprostatic extension identified.
* PIN= prostatic intraepithelial neoplasia41
Review the histopathology report for Ted's TRUS biopsy. Explain the implications of the findings in terms of risk strata.
Describe how you would assist Ted and June to understand PSA and Gleason scores.