First, let me say I empathize with your doubts about decisions and outcome.
My mom was operated on twice in one summer in the early 60s in a small city, 100,000+. We nearly lost her.
First an exploratory surgery (horrors now superceded, largely by various imaging and tests) and then a protracted operation by a youngish, over aggressive FMG ob-gyn that apparently bulled mom's operation through when his more senior partner, and my mom's primary doctor, was out of state for several weeks. For a while he was a real butcher in his career development, with many victims with unhappy, quietly scandalized families whispering. Her operation was similarly a long snipe hunt thru lymph nodes over 9 hours for nonexistant mets, where she "died" three times on the table and re-started. She suffered serious damage and complications during 2 months unsteady recovery in the hospital, at the point of dying with both kinds of out of body experience, going toward the Light, and the eiditic recorder in corner of the room observing everything. It was about 6 years before she recovered to a plateau, but still not well as before.
The surgery appeared unnecessary as it turned out - no cancer detected in the pathology work up.
Just some hot words from the senior dr when he got back, and not long after, disassociated from the senior dr.
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Fast forward almost 50 years, and we are shopping for that 2nd surgery, for PALN. After several strikes and a line ball, we got a lead from one my wife's friends, from a large family of doctors, on who's best in the region. This was the top surgeon at the top hospital (duh!), specially trained in Japan, with thousands of LN dissections, where other local surgeons' arrogance melt or whither at this guy's name, including the insurance company's consultant surgeon (nasty and discouraging but he signed off on insurance's paper quickly). The "line ball" was an ex-MD Anderson thoracic surgeon at the previous generation's top hospital. "Our" surgeon teamed with another senior surgeon who would first try his robotic surgery station for a laproscopic resection. When adhesions slowed the robotic surgery, they switched to an open surgery where "Zorro" took the lead, they gutted her, got the para-aortic conglomerate out in under 45 minutes (35 min??) for my visual inspection, and they replaced her intestines. I was amazed, I had barely settled into the couch for a much longer wait.
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Although your drs nominally confirmed the elevated CEA reading, my personal view is that they missed a lot of blood data for a such likely mCRC case.
We were pulling blood for chemo at three week intervals the previous year and two week intervals going into surgery for non-standard extra options and total awareness. Under favorable sampling conditions (low inflammation and cell damage), the extra tests might help resolve those questions up front and after. My advice to others is, do more consults (three per critical specialty if possible - difficult for working patients) and more bloodwork.
Surgeons often have surprises that require decisions in real time. We are largely at their mercy and skill.
Your surgeon will simply want to move on once she runs out of helpful answers, and especially if you are restive - a threat to her standing.
I think the lawyers would want a slam dunk case, and the recovery of any cancerous tissue muddies the judgement issue, likewise the elevated CEA at 15-17 that then returns to baseline of CEA ~ 1. Table time simply translates to risk and surgical injury.
For wound healing and recovery, we felt that enhanced nutrition, beyond "std", made a difference, including IV vitamin C and home made super"Ensure". There are number of nutritional claims for some neurological recovery that are nonstandard but that I found credible possibilties.
As for chemo, our surgeon indicated getting the major masses would likely improve or re-sensitize our oral 5FU formula.
I remain an advocate of ADAPT+++ for small residual masses as a potential option with low side effects. Similar chemo served us well too.