- When tumors are described by way of its differentiation, i.e. well differentiated, poorly differentiated, what they are talking about is how close or how far away is from a normal one.
- In prostate cancer the Gleason’s score is a way to describe how a cell is differentiated.
- A Gleason 6 is a well-moderately differentiated cancer.
- A Gleason 8 or above is a poorly differentiated cancer.
- A well differentiated prostate cancer is harder to call for the pathologist than a moderately differentiated cancer because the well differentiated cell more closely resembles the normal prostate cell.
- A poorly differentiated prostate cancer cell is an easy to call for the pathologist because its architecture is so far removed from how a normal cell looks…it is sometimes described as “bizarre.”
- A poorly differentiated cell however can be tricky for the pathologist because it can be so bizarre looking that it loses all the characteristics of a prostate cell.
- So if a patient has a lymph node somewhere and the doctors don’t know the primary cancer (i.e. the origin of the primary cancer) and it is biopsied and it comes back as a “poorly differentiated cancer” the pathologist sometimes can’t tell you where the cancer in the lymph node is from…it is too bizarre to categorize.
- Poorly differentiated cancers are very aggressive, usually don’t respond well to treatment and the patients that have this type of cancer don’t do as well as those as ones with well differentiated cancer.
- Gleason’s 6 patients as a rule will respond to treatment better than a Gleason’s 8 patient.
- Gleason’s 6 well-mod differentiated , Gleason’s 9 poorly differentiated.
- If some prostate cancers don’t produce a high PSA then this makes the case of being sure a rectal exam is always done. That patient who avoids a rectal exam thinking that “I am Okay, my PSA is normal” runs the risk of having prostate cancer and not knowing it.
Now to the question. A poorly differentiated prostate cancer with bizarre features under the microscope can be so “cancerous” that it also has lost the functions of a normal prostate cancer cell.
In this case the most probable reason for a low PSA and an aggressive prostate cancer is that the prostate cancer cell is so bizarre it has lost some of the normal functions of a normal cell and in this case the ability to produce PSA.
Gleason’s score is another way that is prostate cancer specific to describe the differentiation of the cancer and in turn gives one insight to the aggressiveness of their disease.
I have had patients come in for their path report only to find that the pathologist has called one of the cores as suspicious and that more time and stains will be necessary to “call” the diagnosis. I have told them that in some ways this type of report is a good thing. I have said, ” The bad cancers are the easy ones to call. So you either don’t have prostate cancer or it will be a low Gleason’s or the good kind.” My fear for my biopsy was not that I would have cancer, but that I’d have “the bad kind…the Frank Zappa kind.”