Prostate Cancer Staging (Cells, Differentiation, Gleason Score)

December 5, 2009 by Prostate Dr.

The First Cell

The body is made up of cells, organs and tissues. But here is the magic part: all of these different cells are derived from the single cell that resulted from the fertilized egg. So, as the embryo grows, the cells multiply and change, or differentiate, into whatever cell type is the basic brick/building block of a particular tissue or organ. The initial cells are what is called embryonic "stem" cells and they are at the basis of some of the modern "cancer cure" theories.

Normal Cell vs. Cancer Cell

The characteristics of normal cells

The normal cells in our tissues have a number of important traits.

Here are the most important few:

Reproduce themselves with precision
Stop reproducing at the right time
Stick together in the right place
Self destruct if damaged
Become 'mature', or specialised

Cells in carcinoma of the prostate (and al cancer cells in general) are different to normal cells in several ways. These are some features of prostate carcinoma cells:

They go on reproducing, even after they have doubled 50 or 60 times. Eventually a tumor is formed that is made up of billions of copies of the original cancerous cell. This is why scientists sometimes call cancerous cells as 'immortal'.
They don't obey signals from other neighbouring cells- otherwise they would stop growing and stop damaging the part of the body where they grow
They don't stick together, thus they become detached and can end up in other parts of the body.
They don't become specialised, they remain immature and tend to become even less mature with time
They don't die if they move to another part of the body, but survive and sometimes provoke new tumors in those parts: specialists say that "the cancer has metastasized"

Prostate Cancer Cell Differentiation

When a cancer develops, it may have several different types of cells. There are basically three types of cells, as far as differentiation factor is concerned:

well differentiated cells- are cancer cells that are very similar to the original prostate or whatever type of tissue it is
poorly differentiated/undifferentiated cells- are cells within the tumor that bear no resemblance to the original cells at all.
moderately differentiated cells- Between the previous two extremes.

The process of cells becoming poorly differentiated or undifferentiated is sometimes called dedifferentiation. And the job of deciding how differentiated cells are is that of the pathologist, when s/he analises biopsy samples.

If you hear your doctor talk about the grade of your cancer (this is the Gleason grade, used to assess the Gleason score), s/he indirectly means differentiation, or how well developed or mature the cell looks under a microscope.

Some plants and lower animals retain a large amount of undifferentiated cells throughout life. There are so many undifferentiated cells in some plants, such as the geranium, that all you need is a small piece of a branch to grow or clone a complete new plant. Some lizards can lose a part of their tail or a foot to a predator and the tail or foot will eventually regrow from embryonic type undifferentiated cells. If we could find out how the lower animals do this perhaps humans could do it. Studies are being done using human embryonic tissues, even though some people are protesting such studies.

Gleason Grade/ Gleason Score

The Gleason drawing:
the numbers indicate
Gleason grades

The basic idea is: The more normal a cancer cell looks like, the more it will behave like one

The more normal a cancer cell looks, the lower its grade and the less aggresive the cancer is supposed to be. Grade 3 tumors seldom have metastases
The more abnormal or less well developed a cancer cell is, the higher its grade. Stage 4 and stage 5 prostate cancer are common indications of metastatic expansion of the prostate cancer

When the process of differentiation is "out of control", we have a prostate cancer. Most prostate cancers may have a mix of many different stages of differentiation. The Gleason Score for staging prostate cancer is based on the mix of the differentiation of the cells.

Gleason Score

The gleason score is a system for grading prostate cancer. The Gleason grading system assigns a grade (number) to each of the two largest areas of cancer in the tissue samples, as mentionned previously.

The two grades are then added together to produce a Gleason score.

2 to 4 is considered low grade
5 through 7, intermediate grade
8 through 10, high grade

If the Gleason score is low, this indicates that the tumor grows slowly enough that it may not pose a significant threat to the patient in his lifetime.