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Signatera CT DNA Test: What numbers have you seen on your tests?

Posted by gamaryanne @gamaryanne, Dec 10, 2024

We do this test periodically (I was diagnosed 11/2021).

What type of numbers have you seen return on your tests? I don’t know if the scale on the results chart is designed based on my range or the bandwidth of the trial. I hope this makes sense.

Just trying to understand the range since it gives negative or positive Vs the CA19-9 test with a normal “range”.

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marienewland | @mnewland99 | Jan 25 6:23am
In reply to @mnewland99 "Are you basically saying that the Signatera is more accurate at diagnosing microscopic residual disease (is..." + (show)
@mnewland99

Are you basically saying that the Signatera is more accurate at diagnosing microscopic residual disease (is the same thing as microscopic cells lingering about which can lead to metastasis?) than the Guardant360 which goes by blood work rather than tissue? I just got Guardant results online (dr out of town) and it didn’t detect any mutations, including KRAS. These type of tests are all new to me so I dint know anything about them yet. Seems like Guardant360 is good for deciding which clinical studies might be appropriate; but I dint know for sure if this is the purpose of the test. Originally, I thought it was to detect those sneaky microscopic cells.

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Actually, correction on my above response. There were a lot of mutations detected from my Guardant360 testing, but apparently they were predicted to be benign or unknown significance. TP53 was present, but of unknown clinical significance. No KRAS in this sample, though was detected in tissue of pancreas following my surgery back in 2022.

REPLY
markymarkfl | @markymarkfl | Jan 25 5:15pm

Guardant (blood only) is just looking for mutated DNA in your blood. It reports mutation types and tumor mutational burden, but does not discriminate by tumor origin.

Signatera (blood) reports only the number of DNA molecules in your blood matching the DNA from your original tumor tissue, but doesn't tell you anything about mutations.

Tempus NGS (Next-generation sequencing) can tell you about mutations in the original tumor tissue.

My original Guardant test reported the ATM mutation. My second Guardant test detected that plus the CHEK2 mutation.

My Tempus test reported ATM and KRAS G12D, but not CHEK 2.

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marienewland | @mnewland99 | Jan 25 8:56pm
In reply to @markymarkfl "Guardant (blood only) is just looking for mutated DNA in your blood. It reports mutation types..." + (show)
@markymarkfl

Guardant (blood only) is just looking for mutated DNA in your blood. It reports mutation types and tumor mutational burden, but does not discriminate by tumor origin.

Signatera (blood) reports only the number of DNA molecules in your blood matching the DNA from your original tumor tissue, but doesn't tell you anything about mutations.

Tempus NGS (Next-generation sequencing) can tell you about mutations in the original tumor tissue.

My original Guardant test reported the ATM mutation. My second Guardant test detected that plus the CHEK2 mutation.

My Tempus test reported ATM and KRAS G12D, but not CHEK 2.

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Thank you for your explanation. My dr said through MyChart that it’s a good thing that the Gaurdant didn’t identify any KRAS; from your understanding would you agree with that? Does that just mean that aren’t any active rumors that are shedding?

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markymarkfl | @markymarkfl | Jan 26 2:45pm
In reply to @mnewland99 "Thank you for your explanation. My dr said through MyChart that it’s a good thing that..." + (show)
@mnewland99

Thank you for your explanation. My dr said through MyChart that it’s a good thing that the Gaurdant didn’t identify any KRAS; from your understanding would you agree with that? Does that just mean that aren’t any active rumors that are shedding?

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I'm honestly not sure what to make of the discrepancies in those reports. The Guardant 360 page says it detects KRAS mutations (and includes "Copy Number Amplifications"), but I don't know if the breakdown into KRAS subtypes (like G12D) are included.

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marienewland | @mnewland99 | Jan 26 3:25pm

I dint know but my guess is yes because the info I got on the other mutations was very specific. I just want to know if it means there’s no active cancer right now. But I guess it’s always “sleeping”?? It would be great if I could take a real break from chemo.

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