KRAS mutation "indeterminate"

[LMighty]

For some reason I asked our onc for a short written report on my mom's overall situation. He mentioned in the report that KRAS mutation was "indeterminate". This surprised me as I was told long ago that my mom was not a candidate for Cetuximab, and I assumed automatically my mom has mutation.

The KRAS mutation testing was done mid-2016 just before chemo started, with firstly sample taken from pleural fluid that contained adenocarcinoma cells. Our onc said the result showed only "a few" cancerous cells and the amount could not yield conclusive result, so he needed to do another test with sample taken from my mom's rectal tissues removed five years ago. Later we heard from him that Cetuximab was not an option for my mom but like I said he did not mention whether KRAS mutation was "indeterminate", until now.

At the moment I am not sure if he is withholding crucial information. I don't feel so as he has been a very caring onc. I am going to talk to him soon on this but would like to know if anyone here has similar experience. Is the detection of KRAS mutation something that could be "indeterminate"?

[Lee]

I don't have an answer, butt by bumping this back to the top, maybe someone who does have an answer will see it.

Good luck,

Lee

[GrouseMan]

Could be the particular genetic testing method done could not determine conclusively that the tumors have a mutation in the KRAS signaling pathway. The tests are usually for specific mutations in the pathway that are the most predominate ones that have been identified through tests on many peoples tumors. Could be your mother has a mutation in this pathway, but they don't know for certain where it sits in the pathway, or exactly what make up the mutation. So its possible that its different than for many folks with a KRAS mutation and they just don't know much at all about it in her case. They can't be sure Cetuximab would have any effect or not most likely. So they are calling it indeterminate. New tests from a fresh biopsy would be best if possible. Mets almost always have different genetic defects (Mutations) than their primary tumors they came from

Good Luck

GrouseMan.

[LMighty]

Thanks a lot for your helpful replies.

They took some tissue for biopsy when the pleural effusion first appeared last year but the result was also indeterminate. All because there was no visible tumor for them to take sample from. They could only test the cancerous cells from the pleural fluid and the sample from years ago.

So this is kind of good news (no visible tumor) in bad news (cancerous cells in pleural fluid) for me. This is going to be on my mind for so long until we figure it out.