Beach sunrise, you've established a baseline of scans. The drs want more size, SUV and PPV (positive predictive value). Hopefully by that time you'll have more papers addressing size-SUV and PPV estimates to wrap around a lead pipe when you interview drs.
People here often get jaded about CEA because of several common complications - varying degrees of inflammation, treatment damage (RT, RFA, heavy chemo), other drug interactions, and low absolute CEA values, e.g. a CEA series averaging 0.9 +0.5 or 1 is rather imprecise. With careful management to avoid chemo damage and inflammation, nutraceuticals and off label anti-inflammatories, with constant test conditions, much CEA "noise reduction" can be had (for newer readers, Beach sunrise has already seen this).
My wife was able to achieve a CEA standard deviation of 0.1 with frequent testing across a year, until a treatment component shortage started 5+ years of slow cycle CEA flares that I visualize as slow sprouting micromets, residuals left over after the 2nd surgery. These CEA flares were heuristically beat down and weeded out for almost 6 years, and then finally subsided. One of my objectives in our first year was that my wife had chemo every day to avoid manufacturing new micromets even though she is considered likely "shot through" with (micro)mets from before initial diagnosis or first surgery. Less micromet inventory to fight later.
For careful patients that have an early broad range (divided by noise or standard deviation), CEA can be a sensitive tool observed and calibrated against various events, especially pre- and post surgery, and other (extra blood) tests.
As for beach sunrise, she has to balance her body's long term chemo tolerance against a likely met(s) that has apparently been largely controlled by her impressive chemical stack minus slippages but now slowly rising vs imaging to define surgical targets as feasible. Where she is on imaging is near the limits of PET-met sensitivity in that gray zone, above the SUV-size cutoffs for a clean scan but no met yet clearly defined by imaging alone with a high PPV, yet. This where a careful history and the extra blood work may help time future scans, or a thoracic or oncologic surgeon move sooner than (too) later.
watchful, active researcher and caregiver for stage IVb/c CC. surgeries 4/10 sigmoid etc & 5/11 para-aortic LN cluster; 8 yrs immuno-Chemo for mCRC; now no chemo
most of 2010 Life Extension recommendations and possibilities + more, some (much) higher, peaking ~2011-12, taper to almost nothing mid 2018, mostly IV C