My mum is in treatment for Stage 4 Adenocarcinoma and recently had her ALK genetic mutation testing results which state - 'no ALK gene rearrangement, but additional copies of ALK gene locus detected'. Her oncologist explained that this means she is Negative for ALK gene mutation but could not explain what 'additional copies of ALK gene locus' means.
What does 'additional copies of ALK gene locus' mean?
Could you explain if this has any effect on her possible genetic mutation status?
We would like to be sure that we fully understand the implications of her ALK testing before we proceed to testing for the more rear genetic mutations such as ROS1.
Reply # - February 13, 2013, 08:40 PM
The ALK testing is based on a threshold of a certain level of copies (in 15% of nuclei) of the ALK rearrangement being detected, and above it, testing is called positive. To my knowledge, it isn't known whether having some lower level of detectable ALK rearrangement means anything for predicting response to crizotinib, nor for the probability of another "driver mutation". Up to this point, less than the defined threshold of ALK rearrangement is simply considered "negative" for the purposes of research on molecular testing in NSCLC.
Reply # - February 13, 2013, 09:13 PM
This transcript should provide enough of a biology lesson about ALK gene rearrangement to feel comfortable about moving forward with molecular screening for your mum and being sure the proper testing has been done for ALK.
The following posts are on molecular testing in general and I think will provide an understanding without delving so deeply into the biology that moves away from our focus of what tests and treatment is best.
We have an extensive library that I find best accessed by using our search feature. Note you may need to log off to access it depending on your browser. I didn't come across any info about your particular question about ALK gene locus’. That doesn't mean you shouldn't ask but it does probably mean you should read what the experts and sophisticated members have discussed on the matter.
I hope this helps,
Reply # - February 14, 2013, 08:39 AM
I don't think it was particularly helpful of the testing lab to have worded their report so that even the oncologist couldn't understand it. It seems to me that you have two choices: either take his/her word for it or, if you want a fuller picture, contact the testing lab for clarification from a pathologist, asking the question you have just asked - does it have any bearing on testing for ROS. Best to you and your mother.
Reply # - February 14, 2013, 10:25 AM
Sorry to be a pessimist here, but I would be floored if someone at the lab actually has a meaningful answer. They probably didn't write the wording on the reports and wouldn't have any more insight.
Reply # - February 14, 2013, 12:50 PM
Thank you Dr. West and everyone else. This has been very useful and incredibly quick way of preventing an endless, inconclusive Internet search for answers.
We needed to fully understand as the next step for genetic testing is not available in New Zealand where my mum lives and we will have to go through quite a procedure to get tested in Peter Mac in Australia and hopefully be able to see Dr. Ben Solomon.
Thanks again and all the best to everyone.
Reply # - February 14, 2013, 08:03 PM
Peter Mac and Dr. Solomon have been among the leaders in the world in a lot of targeted therapies in lung cancer, and especially work on ALK, so if there's anyone who could answer your detailed questions, it's him.