Prognostic value of first negative Signatera test performed two yeras after surgery

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I_will_fight
Posts: 103
Joined: Mon Jun 29, 2020 3:38 pm

Prognostic value of first negative Signatera test performed two yeras after surgery

Postby I_will_fight » Thu Aug 04, 2022 1:10 am

Hi all, I was dx stage II high risk and underwent left hemicolon surgery in july 2020 followed by 3 months CAPOX.

I had my first Signatera test done in june 2022, almost two years after surgery.

The results are negative (as is no trace of ctDNA could be detected). Obviously this makes me very happy.

Now we all know Signatera is not very sensitive (I am reading 50-60% sensitivity on a single measurement). We also know that Signatera is not very good at picking lung mets (which are unlikely to be the first metastasic site for colon cancer anyway)

Do you think that the fact that I had this test done almost two years after surgery may improve it? I mean at least theoretically, by now if viable cancer cells had been left in the body they should have already multiplied enough to be detectable, shouldn´t they?

I will obvioulsy continue my surveillance and repeate Signatera over the next few months but I wanted your opinion.

Thank you and best regards

Javi
46 yo male Spain
06/20 - 6cm T3N0M0 CC splenic flex
No liver mets, 3 and 4 mm lung dots (unlikely to be mets)
lymp 0/37
MSH6- other MMR+
KRAS mt G13D
V/LNI absent
PNI present
07/20 - hemicol surg, 13cm clear margins, optimistic surgn.
08/20 - CAPOX regime, 4 cycles.
11/20 - CAPOX completed. CAT scan: lesion in liver, suspect hemoangioma, no changes lung dots.
12/20 - Clean colonoscopy
02/21 - MRI liver lesion is nonspecific, stable.

MadMed
Posts: 166
Joined: Sun May 02, 2021 5:52 pm
Location: Massachusetts

Re: Prognostic value of first negative Signatera test performed two yeras after surgery

Postby MadMed » Thu Aug 04, 2022 10:32 am

I think you are as well informed as possible. With all the caveats you listed, it's a good sign. One thing I wonder is about the initial signatera draw. They need to have a biopsy of some kind (tissue or liquid). Did you have that done ?

Edit: I saw your other post, so you had the first draw with the tumor markers.
52M DX: RC lower rectum, guessing now 2cm from AV 4/27/2021
T3N0M0 adenocarcinoma with signet ring cell features
Tumor size 30mm
Tumor grade: G3
Baseline CEA 1.0
MSI status: MSS pMMR
Started Folfox 5/12/2021
Switched to FOLFIRINOX from session 2. 8 rounds total.
CT+MRI tumor contained shrunk 80%, no spread to other organs.
CRT started xeloda + 28 days Radiation 9/27-11/04
NED as of 4/06 CT/MRI/sigmoidoscopy
On W&W 04/06/2022

I_will_fight
Posts: 103
Joined: Mon Jun 29, 2020 3:38 pm

Re: Prognostic value of first negative Signatera test performed two yeras after surgery

Postby I_will_fight » Thu Aug 04, 2022 12:09 pm

MadMed wrote:I think you are as well informed as possible. With all the caveats you listed, it's a good sign. One thing I wonder is about the initial signatera draw. They need to have a biopsy of some kind (tissue or liquid). Did you have that done ?

Edit: I saw your other post, so you had the first draw with the tumor markers.


MadMed, thank you for replying.

Oh yes, The tissue was put in paraffin blocks after surgery in july 2020 and it was kept in my hospital. Then in june 2022 they took part of this tissue and sent it to the Natera lab. Presumably they use this to identify 16 mutations found in the tumor.

In paralel the drew a tube of blood to see if they could find traces of the mutated DNA from my tumor tissue in the sampled blood. This is what I referred to as "initial draw".

Then I think every few months they will take blood and check for the mutations again. They call this "longitudinal or serial testing"... which repeated over time is meant to provide greater sensibility.

Natera claims 97% negative prognostic value after repeated testing for two years. Other studies say it is not more sensitive than Imaging and CEA together. (But since CEA is not a good marker for me I guess Signatera will be better for me)

Anyhow, thanks again and good luck.
46 yo male Spain
06/20 - 6cm T3N0M0 CC splenic flex
No liver mets, 3 and 4 mm lung dots (unlikely to be mets)
lymp 0/37
MSH6- other MMR+
KRAS mt G13D
V/LNI absent
PNI present
07/20 - hemicol surg, 13cm clear margins, optimistic surgn.
08/20 - CAPOX regime, 4 cycles.
11/20 - CAPOX completed. CAT scan: lesion in liver, suspect hemoangioma, no changes lung dots.
12/20 - Clean colonoscopy
02/21 - MRI liver lesion is nonspecific, stable.

MadMed
Posts: 166
Joined: Sun May 02, 2021 5:52 pm
Location: Massachusetts

Re: Prognostic value of first negative Signatera test performed two yeras after surgery

Postby MadMed » Thu Aug 04, 2022 12:27 pm

Excellent, i think you're in even better shape. Using the tissue is even more precise than blood biopsy. I believe you are in a great spot. You have certainly done everything to protect yourself.

Good luck!
52M DX: RC lower rectum, guessing now 2cm from AV 4/27/2021
T3N0M0 adenocarcinoma with signet ring cell features
Tumor size 30mm
Tumor grade: G3
Baseline CEA 1.0
MSI status: MSS pMMR
Started Folfox 5/12/2021
Switched to FOLFIRINOX from session 2. 8 rounds total.
CT+MRI tumor contained shrunk 80%, no spread to other organs.
CRT started xeloda + 28 days Radiation 9/27-11/04
NED as of 4/06 CT/MRI/sigmoidoscopy
On W&W 04/06/2022


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