How do you know if your cancer has genetic mutations?

A follow up to the original question in this thread. I noticed some who answered have had the guardant or other tests done multiple times. Is there a standard time table for this? My husband had the liquid biopsy in June of last year. Just wondered if we should be pushing to have it done again to see if new mutations following his chemo. Thank you.

Hi @sheridanb, I'm tagging @mnewland99 @ashley2235 @stageivsurvivor @elisabeth007 @markymarkfl @granite @vannkraken to see if they have some knowledge and experience to share regarding your follow-up question:

"I noticed some who answered have had the guardant or other tests done multiple times. Is there a standard time table for this?"

Sheri, have you had a chance to ask your cancer team about frequency of genetic testing or if it needs repeating, why and when?

Germline panels would not need to be repeated because that is your base DNA "genetic blueprint." I don't know how often it might be recommended to test existing tumors from biopsies to see if new mutations have popped up since the tumor was sampled the last time.

It seems like cost, infection risk, etc, might outweigh the value of repeated biopsy testing in some cases (my wife's pancreatic and liver tumors are in pretty difficult places to reach)? Though it is true that new mutations might be the root cause of the cancer evading existing current treatment regimens. I will follow up with her oncologist on this at our next meeting.

i did not have guardant and am not familiar with it. i saw at geneticist at the University of Miami in 2000 and she ordered the most comprehensive genetic testing at the time. i did not have cancer and fortunately have not had cancer yet. No oncologists were involved in the genetic testing decision making. However, my neuro-opthamologist was involved because my eyes were exhibiting potential symptoms of a “movement disorder”. i tested negative for a movement disorder but had an incidental finding of an ATM gene mutation. That mutation places me at high risk for breast, ovarian and pancreatic cancer. I am on high risk protocols for all three forms of cancer. And then i’m on high alert monitoring for my meningioma. At times, i feel like i “live in an MRI tube”. i did not get the sense that i was expected to have followup genetic testing and i’m
not going to suggest it. At this point, i feel i may know more than i wish to know about my potential health risks. i want to focus on maximizing my quality of life. I spend too much time in medical facilities

i just read about guardant. I had a very different type of genetic testing done.

whole exome sequencing is the type of genetic testing i had

Hello sheridandb,
For me, before my surgery, I received the Ambry genetic blood test (Ambry probably because its inventor is local to Orange County). After my surgery, my pancreatic tumor was tested and 4 mutations were found. Mutations revealed were KRAS12D, ATM, TSP-*. I dint have them, but there are some mutations (BRCA, KRAS12C, D) that have treatments specific to them. After surgery, I did the standard 5FUchemo for 6 months. It SEEMED to work with the exception of hepatic artery spread that occurred prior to starting chemo as 4 months following completion of chemo my cancer spread to liver and maybe abdominal peritoneum.Biopsy was done for liver and biopsy for peritoneal nodules and hepatic artery was inconclusive; no additional pathology was done on this biopsies. GAC chemo has history, in some cases, to be successful for liver cancer (and lung cancer). GAC was working ok until I took a chemo vacation and it seems to have spread to femur. I personally don’t think it’s necessary to repeat your baseline genetic testing, but most likely the somatic testing could be repeated to determine any new mutations if you already have ample tumor tissue that could be tested. Maybe you repeat somatic if you find early on that you aren’t getting a response to chemo or radiation? It seems drs could be more proactive, but it depends how much existing tumor tissue you have available to test.

Regarding frequency of genetic testing for somatic mutations, I have asked a number of geneticists this question and the consensus is at least four years. There are not enough new pathogenic mutations found to justify the return on investment. I’ve had testing repeated times in the past 12 years and it has not revealed any new mutations.

We just returned from Fred Hutch in Seattle. Second opinion with doctor there and I asked if we should have the guardant done again, and he said no. And our oncologist here did not seem to recommend it either.

I had two Tempus blood biopsies and a Signatera CtDNA. The Tempus blood biopsies identified that my cancer had the BRAF mutation.
My pancreatic cancer was caught at Stage 1A and all blood biopsies and Signatera have come back negative. I am presently being monitored with CT scans and blood biopsies to catch any possible micro metastasis.
In the event of this happening, I would be put though six months of Meknist and Sorafenib which are kinase inhibitors. Identifying which mutation I had, allows for a more targeted treatment approach.