Use of Signatera testing in stable disease
I just had my latest scans, and I am still stable with my current treatment plan- Lynparza, Lupron, Xgeva. In fact, the scan said "no evidence of metastatic disease in the abdomen"- I had tumors in the liver we were monitoring. I ask my MO if there was any way to monitor molecular progression- progression before it is large enough to show on a scan. He said for me to read up on the Signatera test and let him know if I wanted to do that test.
As you can see from my profile, I got 4 years out of Ibrance before I had progression. And I am 3+ years on Lynparza as my second line therapy.
My question to the group is - have any of you read the research about using the circulating tumor DNA testing outside of when you have progression and trying to decide on the next line of therapy? Instead, just using the test to monitor the stability of the disease. What does the research say about changing treatment based on the ctDNA results versus the scan results?
I do not do tumor markers, as they are unreliable in my case. My history showed elevated TM's, but not too elevated even when I had large tumors in the liver. And they only dropped a few points when the tumors shrunk.
I just don't know if I want to do the Signatera testing if it would not give good information (waste of money), and if I should move to another treatment if the Signatera testing suggested it but yet I still have stable scans.
Thoughts….
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Someone posted to me on another Thread and said that her MO does Signatera monthly with scans every 3 months. She is TNBC though, so very aggressive. I don't know if that makes a difference. But that her MO uses Signatera to monitor for early changes. Hum…
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Hi Candy. It's been a few months being on BCO. Today is a rainy, cold day, so what the heck, trying to catchup. Sadly, so many new names but thankful to see folks like you who are on the threads for a while.
I receive ctDNA monitoring with the Guardant Reveal test for minimal residual disease (MRD). I receive the blood test quarterly and PT/CT scans every 6 months. Thus far, my results are negative for detection of circulating tumor in the blood. Oncologist would bump up scans if a positive result. She would not change treatment based on this test alone.
This test is FDA approved but my insurance does not cover it. Guardant does have a generous sliding scale based on income. I was informed most people pay nothing or max $25 per test.
Glad to hear you remain stable. No TM for me either, Oncologist feels ctDNA are more accurate for disease progression then TM. Take Care.
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I think we will always need a follow-up scan as confirmation and clarification of any blood test results, but signatera (or other ctDNA testing) can be a good early warning sign and seems more accurate for more people when compared to the tumor marker tests.
The study I am on is using Signatera in conjunction with CT scans to monitor for progression/recurrence.
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Thank you tinkerbell and olma. I do remember you tinkerbell. I have been on this site for several years.
I get scans (chest CT and abdomen MRI) every 4 months. I was getting them every 3 months, but since I am stable, I asked my MO if we could push out to every 4 months, and he said Yes. If we would start the ctDNA testing quarterly, then it would only be the next month that I would be due for scanning anyway. So I don't know if that would be worth doing the test. Doing them monthly would be more helpful, I would think, as then we would really be on top of anything brewing. But, since I am stable, and not triple negative or really aggressive, and not on a clinical trial, then monthly may be overkill.
Anyone else with thoughts, chime in.
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May I comment that I think you should have the test. I had it 3 weeks ago and it showed a positive with elevated tumor markers. I have a CT scan tomorrow. I am at high risk for recurrence and had the test done 2 years ago. It was negative. My Onc. Didn't test it for 2 more years and now a strong positive. So I am now Metastatic. IF he had done it every year, Which I didn't know was an option, or even every 6 months, we could have caught it sooner and started treatment sooner.
I am on Medicare and the test is free for me. I encourage everyone who is 2b or higher to get it. I realize our circumstances are different, but I mainly write this for anyone looking at Signatera testing.
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hippmark,
I am still confused. Where have you metastasized to? Again, I could be wrong but what are you treating if you don’t have a specific metastatic site or sites? There have been many changes in treating mbc in my 13+ years here but am not familiar with tx for unspecified metastasis.
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I will know tomorrow after I have the CT scan. Please allow some grace. High CTCdna scores plus abnormal 25-29. I'm sorry, but I don't have the bandwidth right now to go into this further. And yes, with high CTDna, some Oncologists start treatment as they already know you have metastisis, new tumor found YET or not. It's already formed or forming.
If I need to stop posting until they have found the tumor, say tomorrow, I will do so
Looking for support here, not more stress trying to defend what I know and have already been told by Doctors.
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Sorry if you felt unsupported. My questioning actually was support in that I am trying to say you may not be stage IV/metastatic since metastasis is specific to another organ/structure. There is no general metastasis with breast cancer. My apologies and it is my sincerest hope that you are not stage IV.
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hippmark- I do think they use ctDNA testing for early-stage folks, to look for reoccurrence. Like with you, to diagnose potential Stage 4.
But I was asking about Stage 4 folks using it as a method of looking for progression before it is seen on the scans we have every 3-4 months (our usual protocol of scanning). Some Stage 4's use "tumor markers monthly- CA 15.3 for example- to monitor for progression. If their numbers go up then they scan early, but that has not been a good indicator for me.
So I am asking about using this method of monitoring with Signatera very often, not just periodically. Like monthly, or every 3 months.
I hope you find you are not Stage 4. I hope your CT comes back clear.
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You absolutely can use it for monthly or quarterly screening purposes and my traditional Medicare does pay for it. (Plus they have financial assistance programs if not).
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@candy-678 I will share my recent Signatera testing experience: I was diagnosed with stage IV in June 2024. One bone met in sternum and possible mass (never biopsied) in soft tissue behind sternum tumor. I had 4 courses of HP protocol and anastrozole starting end of July 2024. In September 2024 I had another PET/CT scan and was NED. I chose to take a "treatment holiday" for three months. My MO then suggested I start Signatera testing. I had my first Signatera test 3 weeks after NED PET. Signatera test was negative. Six weeks later I had another Signatera test which indicated extremely low positive. Four weeks later had another PET/CT. This one showed slight uptake behind sternum. We initiated HP and anastrozole again in January 2025. I had another Signatera test in January 2025 before starting treatment again. This test was again extremely low positive. My MO suggested having Signatera tests following each PET to see if the scan and ctDNA results align. I just had another PET/CT Monday. It indicated a reduction in the soft tissue uptake, but some uptake in the sternum spot again. I will get another Signatera test when I go in for my HP infusions next week. We will see if they align with the most recent PET. So, basically, I will now get the Signatera test every 12 weeks following my PET/CT.
In addition, I get CA15-3 and CA27.29 tests every 3 weeks. They have remained in the normal range since July. Both were slightly elevated when I was first diagnosed. It seems that my tumor markers do trend somewhat, but the ctDNA test seems more reliable, in my case anyway.
Natera, the company that does the Signatera tests, has "counselors" who you can speak with (once you are getting the test) at no charge and ask LOTS of questions. I did just that. There is still a lot that they are learning from these tests.
My MO feels they are an added piece of information, but does not rely solely on them. That being said, once I finish my 5 courses of radiation to the sternum due to the new uptake in that area and, if I return to NED on PETs, but the Signatera test after the PET indicates positive, there will be the concern as to where the new metastasis might be, given I just had a clear PET. That is where the conundrum exists. It will be interesting to see if my PETs and Signatera tests continue to align or not.
Natera is willing to work with patients regarding cost because, I believe, they are trying to see trends to determine how well these tests actually predict recurrence.
Best to you and do let us know what you find out regarding your testing.
Hugs, Pam 💗
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Livinglifenow- Good info!!! I just saw my MO (with scans), and he said for me to research Signatera and let him know next time if I want the test. "Next time" is July. So I am filing this info away until closer to then to make a decision. But sounding promising to maybe do the blood test. Then discuss with MO on how often I should do the test, and how to work it with the scanning schedule.
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@candy-678 It’s great to have options. Wishing you clear scans!
Hugs, Pam💗
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