Understanding What Makes Gleason Grades Different

An article published last Friday by MD Anderson sheds light on why less differentiation makes higher Gleason-sum PCa more lethal:

www.sciencedaily.com/releases/2012/05/120504135929.htm

They found that there are two types of PCa stem cell, one rich in PSA, the other expressing little or no PSA. The low-PSA variety not only is resistant to chemotherapy and hormonal therapy, it also is able to divide into either the rich-PSA or low-PSA variant. The rich variant can only beget itself.

The low-PSA stem cell is the one that survives standard treatments, and also produces larger tumors faster. It is the predominant type when treatment finally fails. This tells us why high-Gleason PCa discovered in patients who already have mets even though their PSA is under 10 is so deadly.

The researchers discovered that Gleason 7 PCa samples contained around 80% of the rich-variant; Gleason 9, only 60%. This gives high Gleason cancers double the number of low-PSA stem cells that can resist treatment and are capable of spreading the disease.

Of course, this is only one piece in the puzzle, but it helps to better understand what "undifferentiated" cells of higher Gleason grade can portend.

With discovery comes potentially new treatments. Hope continues to grow.

Nellie

Post Edited (Riviere) : 5/9/2012 8:31:59 AM (GMT-6)

My earlier research left me curious: what percentage of a PCa sample would comprise stem cells? Another recent paper from the National Institute of Health gives at least a hint.

"Long-Term Recovery of Irradiated Prostate Cancer
Increases Cancer Stem Cells," onlinelibrary.wiley.com/doi/10.1002/pros.22527/pdf

Later in this very interesting article, the authors indicate that stem cells comprised only 0.04% of a non-hormone resistant cancer cell line, but up to perhaps 70% of a hormone-resistant cell line. All this is based on currently perhaps inconclusive immunohistochemistry.

Nevertheless, it suggests that the percentages in my first post apply to a very small fraction of the normal non-hormone resistant cancer sample: 20% or 40% of the 0.04% comprising low-PSA stem cells for Gleason 7 and Gleason 9 respectively. That's .008% of the cells for Gleason 7 and .016% of the cells for Gleason 9.

Well, that's enough for one morning. Makes my head spin.

Nellie

Post Edited (Riviere) : 5/9/2012 11:42:53 AM (GMT-6)