Tuesday, January 23, 2007

UKALL 2003 - Dexamethasone 2

I've refrained from tackling this until now as I really didn't understand even a twinkling of the science behind Dexamethasone's anti-cancer properties. After much reading I discover that not even the scientists fully understand the mechanisms.

In my last post on Dexamethasone I attempted to explain its anti-emetic (nausea, vomiting) properties. However, talking to our consultant J. over the holidays, it seems the justification for its use in the treatment of leukaemia is its anti-cancer properties – the anti-emetic effects are a beneficial side-effect.

Right, I'll try and explain what is known about its anti-cancer properties. There appear to be several mechanisms at work:

  • It appears to trigger programmed cell death (apoptosis). Both good and leukaemic cells.
  • They inhibit the production of interleukins which are signalling chemicals which stimulate a variety of cell behaviours. The IL-2 interleukin (there are 33 of them) is produced by T-lymphocytes. The IL-2 then binds itself to the T-lymphocyte signalling it to grow and differentiate. (This self-signalling is termed autocrine). Clearly, inhibiting the production of leukaemic T-cells (or T-cell blastogenesis) is one of our goals.
  • It can also (seemingly) increase the ability other chemotherapy drugs to destroy leukaemic cells

It can also prevent white blood cells from reaching sites of infection. Hence (as with most chemotherapy drugs) there is an increased risk of infection when taking it. Strangely, as the WBCs cannot reach the infection, the white blood count may be seen to go up.

I should also add that one of the lesser known and rarer side effects of the glucocortisoids is induced diabetes - this is what H. suffered from - she got over it but insulin injections in the stomach were no fun. I guess no more dexamethasone for her!

Next in the series is Cytarabine - this is kind of cool!

Update: in the comments Lucia also reports having suffered from diabetes so they have switched her to prednisone.


lucia said...

I also had diabetes from the dex. very scary stuff as my blood sugars were so high and I was unstable, but after induction it never came back and it was the same for H. They said it was our age.

Angus said...

Amazing how little info. on its anti-cancer properties is out there. I didn't really get anywhere until I found Patty Feist's site - and she lists the diabetes side-effect.

Did you take it again in the Delayed Intensification phases?

lucia said...

yeah, I took dex until the start of maintenance (last april) and then was put onto prednisolone as I was suffering so much pain from the dex. If I had stayed on it I would have been on morphine permanently. Now I only have the odd bad week every month where I have to take morphine. J. said it was worth sacraficing the tiny difference of effectiveness for the awful side-effects. When I asked him how is got rid of the leukaemia, he basically said they don't really know but they just know it works! And thats why I made myself keep taking it because he said its an important part of treatment especially in maintenance.