Prostate cancer risk assesment, Gleason and TNM

Gleason grading system

The histological grade (degree of malignancy) of prostate cancer is determined by a pathologist on the basis of a microscopic examination, using the international Gleason grading system. It is based on the histological grade of the glandular structures of prostate cancer tissue or the difference in appearance compared with a normal structure.

The higher the Gleason score, the greater the difference and the more malignant (aggressive) the cancer. A well-differentiated, nearly normal glandular structure indicates low malignant potential, while a poorly differentiated (very much changed) structure indicates an aggressive cancer. The grade of the change caused by the cancer is evaluated on a scale from 1 to 5, so that the two most prevalent (primary and secondary) patterns are separately graded from the sample of cancer tissue. These figures are added up, giving the final Gleason score.

In theory, the Gleason score can vary from 2 to 10, with 10 being the worst score. After the introduction of current advanced techniques in pathological diagnosis, it became evident that low Gleason scores are practically not found in prostate cancer. Thus, Gleason scores for prostate cancer usually range from 6 to 10. The score 6 usually indicates a good prognosis. Approximately 70% of patients with a Gleason score of 6 have a localised prostate cancer.

Very high Gleason scores (8 to 10) indicate an aggressive high-risk cancer. If the Gleason score is 8 or higher, the prostate cancer has often already spread at the time of diagnosis. A higher risk also indicates a higher recurrence tendency. This is taken into account in the individual implementation of treatment. Nowadays, advanced prostate cancer can be effectively treated with various combinations of radiotherapy and drugs.

Gradus

In the older WHO classification, prostate cancers are classified into grades 1-3 according to the degree of differentiation of the cells. The classification is thus cytological.

TNM Staging

The TNM stage describes how much the cancer has spread. The letters T, N and M stand for Tumour, Node and Metastasis. The stage is based on the results of diagnostic tests, examinations and imaging. The TNM staging is as follows: