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Kras Test

Momofbbcc
Posts: 15
Joined: Sep 2014

Our family needs some help understanding the Kras test.  We believe my Dad had it done at the time of his colo-rectal surgery about a year ago.  The report as we read it says the test was done on his tumor site tissue and the Kras gene was not detected.  Does anyone know what this means in regards to his new chemo regimen?  His cancer has just recently spread to his liver and his new chemo regimen is Irinotecan Leucovorin, Fluorouracil and Avastin. We just want to confirm that all these medications will hopefully help him and don't want him to have any medications that won't.  Does anyone know if the Kras test ever has to be repeated?  One of our doctors gave us an RX for getting it done the other day in a blood test.  We are not sure if we should do this or not.  Thinking it can't hurt.  Any help would be very appreciated.

Annabelle41415's picture
Annabelle41415
Posts: 6212
Joined: Feb 2009

I've never had this done as my treatment wasn't prone to the mutation that you talk about.  I'm thinking that if your father has had it tested it would remain the same diagnosis, but if they want to give him another blood test to make sure - go ahead.  It would be better to double check than have him go through a treatment where the mutation has compromised his ability to process the drug correctly.  There is really no need for someone to go through all those treatments if it is not going to benefit him.  You are right - it can't hurt so go ahead.  Hope the results remain the same as he will have much better options open to him.

Kim

Daisy13's picture
Daisy13
Posts: 40
Joined: Nov 2014

Here is a link to an article that you can copy and paste in your browser.  It will likely provide more information than you may ever need regarding the KRAS testing, but it will answer your questions:

http://www.wjgnet.com/1007-9327/pdf/v18/i37/5171.pdf

The NCCN clinical practice guidelines for colon and rectal cancers stipulate that only the normal, not the mutuated, KRAS genes should receive threatment with Erbitux or Vectibix and that testings for KRAS mutations should be performed prior to these therapies.

Judging by these guidelines and the fact that previous testing indicated that your father did not have the mutated gene - the Irinotecan Leucovorin, Fluorouracil and Avastin chemo regimen your father has been prescribed could potentially be helpful to him.

I am not familiar with serum KRAS testing, only the tumor tissue sampling, but perhaps there are newer methods being explored.  I am also not familiar with repeat testings.  Seems the only issue with an additional blood test might be that his insuance may not cover it if it is considered a duplication.  Ask your father's doctor if it might reveal additional information. 

Wishing your father and your family strength in your journey.  ~ Daisy

peterz54's picture
peterz54
Posts: 343
Joined: Feb 2012

We all have the KRAS gene.   A fair fraction of colon cancer patients have a mutated KRAS gene.   KRAS controls some of cell signaling related to growth factors, some of which can promote tumor growth.   In the mutated form the KRAS gene cannot be turned off and growth signals stay on.  My wife had the mutated KRAS and this limited the number of chemo drugs which she could take.  Probably wise to double check your reading of the report.     If your dad is not KRAS-mut then he should have the full range of chemo drugs available to him.    

What I am not sure of is whether a patient can go from KRAS normal to KRAS mut over the course of their illness.  I only mentioned this because it's known that tumors are comprised of many cells lines and these evolve over time which is why chemo often becomes ineffective and tumors can come back with a vengence at the end of a course of chemo.   Your oncologist should clarify this.

Peter 

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