ctDNA - using info to guide treatment?

[hopejunkie]

Hi, I'm trying to learn more about ctDNA testing and how a clinician may use that info to determine treatment. I would love to hear from folks who have had those discussions with their oncologist. When was it done? What did it tell you/clinician? Which test was used? (My father is having his surgery soon and I was told that two weeks after surgery, they would test his ctDNA levels.) Please also share data/resources. Many thanks in advance!🙏😊💕

[JanetteR57]

I had my lung surgery to remove my upper left lobe and a7cm tumour in Dec 2010 and CtDNA wasn't a thing then but as I hadn't had a biopsy before surgery as the imaging showed a large mass that had been discovered when I arrived at A&E some months earlier it was done with clinical urgency. A frozen section was sent off to determine what it was and in my first follow up post surgery I was told the type of lung cancer it had been and that I had tested negative for EGFR which at the time was the only mutation with a targeted treatment available. I didn't have chemotherapy so never did see an oncologist. This can be common for earlier stage cancers although since my diagnosis things have changed and at 7cm I would have been offered chemotherapy. I've been involved in lung cancer research and attended many conferences since Nov 2013 and ctDNA has become a topic of discussion in recent years as originally believed that it would be a way of doing a liquid biopsy rather than the invasive way of obtaining lung tissue biopsies which carry risks of pneumothorax (collapsed lung). However the amount of circulating tissue cells from the tumour are much higher in later stage/advanced cancers rather than early stage so the initial hopes of using this to replace Ebus/bronchoscopy/needle biopsies haven't materialised. Certainly your dad will have a biopsy done on the resected tumour which will be more effective than any earlier testing as tumours sometimes have different characteristics in their mutations which a needle biopsy may miss. It's important to test the characteristics however it's done in case there are targetable mutations - as there are now treatments for several not just EGFR as was the case when I was diagnosed. Lung cancer is now much more personalised taking the characteristics of a patient's PDL1 levels (a protein used to determine whether immunotherapy might help) and tumour (for targeted agents in addition to chemotherapy/radiotherapy or surgery) but many patients still receive surgery alone. this information updated just before the pandemic by the UK's major lung cancer support charity may help inform what's to be expected from his surgery and recovery.... good luck to you both... roycastle.org/app/uploads/2...

[hopejunkie in reply to JanetteR57]

Thank you again, Janette for your insights. My father did have a tissue biopsy where they found the EGFR mutation. He's been in a clinical trial with osimertinib for two cycles before surgery. Surgery is in a week. Tumor shrank considerably with neo-osi but he'll still have the lobectomy through an open thoracotomy. In the protocol, they test for ctDNA 14 days after surgery. I will ask the oncologist (after the surgery) how that info will impact his treatment options. Thank you!! Sending you wishes of wellness.💕🙏

[JanetteR57 in reply to hopejunkie]

Thanks - good that he could have a targeted treatment and surgery...wishing him well for a speedy recovery from it...

[Denzie Moderator Volunteer]

I’m not certain why they would wait two weeks to do the circulating tumor RNA test when they will have whole tumor from the resection. If this was my body I would ask the doctor to explain the reasoning behind the decision for that type of follow up.

You might contact the doctor’s nurse and ask her/him to get an answer from the doctor today (as non ER it might take a couple days to get an answer). If you do that, would you let us know the doctor’s response?

[hopejunkie in reply to Denzie]

Hi Denzie, Please see my response to Janette above with more detail of my dad's situation. I suspect they check for circulating tumor DNA (ctDNA) 14 days after surgery to see if they can find "floaters" after the tumor has been removed. In a recent lecture by Dr. Janne at Dana Farber, he indicated that ctDNA can be a predictor of recurrence. Not surprising but all of this is still being researched. Hope all is well and healthy on your end, Denzie!

[Denzie Moderator Volunteer in reply to hopejunkie]

Loving your answer, I learn something new every day.