American pathologist Donald Gleason devised a method to predict the potential of prostate cancers to grow and spread, thus identifying which methods of treatment to use
When talking about cancers, doctors use the terms Stage and Grade in order to understand the seriousness of any form of cancer and quantify the prognosis.
Staging
The Stage of a cancer gives an idea of whether the cancer is confined to its organ of origin, or if it has spread beyond the confines of this organ. The higher the stage, the greater is the degree of spread.
Prostate cancer is staged using the worldwide TNM system which separately assess the Tumour itself (T), the lymph glands or Nodes (N) to which the prostate gland drains, as well as distant secondaries or Metastases (M). With regard to the T stage, for example, a Stage T1 or Stage T2 prostate cancer is one that is confined to the prostate gland – while a Stage T4 cancer is one that has spread to adjacent organs like the bladder or rectum.
Lymph Node (N) staging ranges from N0 (where no cancer cells found are seen in any lymph nodes) to N3 (any draining lymph node containing cancer cells that is greater than 5 cm in diameter).
Staging for Metastases (M Stage) can either be M0 (where there is no cancer spread detected outside the pelvis or M1 (where secondaries are found in organs outside the pelvis).
As an example, a cancer described as a T2N0M0 cancer would be one which is confined to the prostate and has not spread to either lymph nodes or distant sites.
Grading
The grade of a cancer refers to the aggressiveness of the tumour, and is an attempt to put a numerical value to the likelihood of the cancer growing and spreading. In simplest terms, grading is done by a pathologist who, looking at a specimen of the tumour under the microscope, assesses how abnormal the cells of the tumour look. Many factors – such as how closely the cancer cells resemble normal cells (often termed the degree of differentiation), the number of dividing nuclei in the tumour cells and the size and shape of these nuclei, the structure of the cells and the proportion of cells in the tumour that rare dividing – are considered when determining the grade. The specific factors utilised to determine tumour grade vary for different kinds of cancer.
Donald Gleason (20.11.1920 – 28.12.2008)
It was the American pathologist Donald Gleason from the University of Minnesota in Minneapolis who devised a system of grading for prostate cancers – called the Gleason Score – which is used today to determine the aggressiveness of prostate cancers.
The Score is based on a pathologist’s examination under the microscope of tissue surgically removed from the prostate and stained with special chemicals. The pathologist assigns a separate numerical score to the two most predominant architectural patterns seen under the microscope – ranging from 1 (where the cells appear almost normal) to 5 (where the cells appear most undifferentiated). The sum of these two scores constitutes the Gleason Score – 2 being the lowest (with the best prognosis) and 10 the highest (with the worst prognosis).
Dr Gleason’s scoring system has been adopted uniformly in all scientific publications on prostate cancer since 1987 – and is today considered the most reliable indicator of prognosis and guide to treatment in men with prostate cancer.
Resources:
- http://www.prostate-cancer.org/