Liquid Biopsy - 1274056

baden1
Posts:3

I was diagnosed with Stage IV adenocarcoma NSCLC EGFR Exon 21 substitution three months ago.
I have been on elotinib (TKI) for two months now and responding well.
As I understand it, my cancer will at some stage acquire resistance and depending on how it mutates,the treatment options will differ.
I have the opportunity to submit blood for liquid biopsy ( free circulating ctDNA) as a additional way of monitoring my condition and revealing early signs of resistance
Do you think the technology is proven and reliable yet?
If so would it be beneficial in gaining early detection of resistance?
Thank you
Baden

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Reply # - May 16, 2016, 07:01 PM

catdander
Posts:

Hi Baden and welcome to Grace. I'm so sorry to know of the diagnosis and hope to able to answer some questions along the way.

As of today there's no reason outside a trial to know that cancer may (and that's a big may be) beginning to show signs of acquiring resistance to tarceva. Most often when tarceva shows these signs they are seen on a CT. For now the CT is the only way to know for sure about acquired resistance. Even then it's often a very slow process that can often be halted by a local therapy to the spot or 2 that has acquired resistance while continuing tarceva works systemically for a year or so.

So finding out before any intervention would be made would only cause worry. As well, blood test are not proof positive yet either. A moot point at best, for now at least.

I hope tarceva works for a long long time to come.
All best,
Janine

Reply # - May 16, 2016, 07:02 PM

JimC
Posts: 2753

Hi Baden,

Welcome to GRACE. Currently, the best use of the liquid biopsy is to help determine whether lung cancer is progressing due to a particular mutation such as T790M. In the absence of scan evidence of progression, results from a liquid biopsy are not generally considered sufficient to prompt a change in treatment, as discussed in this podcast.

The best way to monitor for progression remains follow-up scans and clinical examinations.

JimC
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Reply # - May 17, 2016, 02:27 AM

baden1
Posts: 3

Thank you Janine and JimC for your responses.
It has clarified the situation for me and hopefully saved me considerable worry as you have pointed out!
Janine - you have pointed out the use of CT for identifying tumour growth or resistance.
Would you recommend a standard CT or PET/CT for this?
The former is covered in my health insurance but the latter is not!
In a PET/CT I understand you can see how active the tumors are as well as their size but is this worth the expense on a regular basis?

Thank you
Baden1

Reply # - May 17, 2016, 08:50 AM

catdander
Posts:

Baden,

As for now there's little need to add PET to the scan. It's main use in lung cancer is in diagnosis. CT scan is standard of care when following this treatment.

Janine

Reply # - May 17, 2016, 11:50 AM

JimC
Posts: 2753

Hi Baden,

I agree with Janine. The resolution of a standalone CT is greater than that of the CT component of a PET/CT, and since PET picks up inflammation and infection as well as cancer activity, it's not always clear what to do with PET results.

JimC
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Reply # - May 17, 2016, 02:03 PM

baden1
Posts: 3

Thank you again Janine and JimC,
Very sensible advice and a relief ...not least to my wallet.
Best wishes
Baden1

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