CTC counts may be the way of the future...

[Hazelgreen]

Published in Metastatic Breast Cancer and

News · December 16, 2022

SABCS 2022: Using Circulating Tumor Cell Count to Guide Treatment Decisions Improved Overall Survival in Patients With Metastatic Breast Cancer

Patients gained 16 months in median overall survival if they received chemotherapy due to high CTC count over investigator-recommended endocrine therapy

[Claireperth]

Hello, is a circulating tumour marker cell count the usual marker oncologists refer to? Thanks Claire

[Hazelgreen in reply to Claireperth]

I think so. According to cancer.gov/about-cancer/dia... "Circulating tumor markers can be found in the blood, urine, stool, or other bodily fluids of some patients with cancer. Circulating tumor markers are used to: estimate prognosis, determine the stage of cancer, detect cancer that remains after treatment (residual disease) or that has returned after treatment, assess how well a treatment is working, monitor whether the treatment has stopped working"

[TammyCross in reply to Claireperth]

Probably not. They are more often referring to tumor markers -- there are three blood tests for tumor markers.

[TammyCross in reply to TammyCross]

From Google search: A circulating tumor cell (CTC) test is a blood test that looks for tumor cells that were shed from a tumor and are now moving (circulating) through the bloodstream. Currently, CellSearch is the only FDA-approved CTC test for metastatic breast cancer.

If you look it up, there are many uses for CTC tests: taking one early on and after starting Rx tells whether Rx is working; tracking the spread; prediction; etc. It is still considered more of a research tool than standard clinical practice.

[Claireperth]

So is this article suggesting discarding Ibranc etc and going straight to chemo?

[Hazelgreen in reply to Claireperth]

Only if your CTC count (not your tumour markers, see Tammy Cross' comment above) is high...

[RedAzalea]

CTC testing is completely different than traditional tumor markers. A friend of mine with MBC -treated at UCLA - was just tested with NATERA. Basically it’s a much more accurate test than tumor markers. If I understand it correctly, in layman’s language, they search to see if your mutations are present - PIK, or ESR1 for example.

It seems it will be a major tool in the future to target treatment or to stop/ lessen treatment. right now it’s VERY EXPENSIVE and my Onc at MSK said insurance isn’t paying as they are awaiting FDA approval.

I suppose “maybe” this is the follow up to Oncotype DX testing for early stage BC???

Here’s Natera’s site:

natera.com/oncology/signate...

It’s all cases, it’s ALL about “the mutations.” It’s the future of all metastatic cancer treatment.

[Hazelgreen in reply to RedAzalea]

Thanks for all the info!

I, for one, am wary about switching treatment based on tested mutations. I already know, for example, that my liver tumours tested positively for the PIK3CA mutation last spring. Fortunately, my liver continues to function well (no enzymes in the abnormal levels), and my oncologist has continued Kisqali treatment which seems to have brought my cancer markers down to a near-normal level with reasonable side effects. I am not looking forward to the side effects of alpelisib–fulvestrant whenever I may have to switch to that treatment...

[TammyCross in reply to RedAzalea]

Interesting. I will see if I can get Natera. There is a simpler -- or more common and likely to be covered by insurance -- liquid biopsy (blood test) that can find mutations, however: FoundationOne CDX. It is a genomic test that looks at solid tumor DNA.

[RedAzalea]

As far as I understand (and my understanding is at best very shaky), it’s based on if the mutations are circulating in your blood, not on “having a mutation”.

Apparently, if they it detect circulating, you will experience progression. 😻

[Split]

“Bigard noted that a main limitation of the study is that during the STIC CTC study follow-up, CDK4/6 inhibitors (palbociclib, ribociclib, and abemaciclib) became largely used as first-line treatment, therefore, doctors are more likely to recommend front-line hormone therapy combined with CDK4/6 inhibitors rather than chemotherapy”.

[jersey-jazz]

Thank you, Cindy, for your continued efforts to research our MBC situation. You are doing a great service to us.