Don't know about what blood tests they got when you got your colonoscopy, but we found we wanted more blood information than were taken at diagnosis, before and after surgery. In fact, one of my parents' had better blood data taken in the 1980's than we did in 2010. Better early information (before and after surgery) might have saved us a lot of grief and uncertainty; better data certainly helped us when we got it.
In any case, inadequate initial blood data is a serious problem that I've always encountered. Ordinary doctors and hospitals are usually varying degrees uncooperative on non standard tests that actually have cumulative long term consequences on (y)our options. But people can order their own blood tests online or on the phone.
The more specifics you can measure or document here,
(extra) blood tests, pathology, and scans, the more chances you might find more answers, even less known world class options if necessary. Many people use their signature to summarize these.
It is important to not let any potential mets or micromets grow unchecked, some kind of treatment plan ASAP is important. Self-advocacy, reading/expertise, and a careful, action orientation are important factors.
My belief is that if you want to stay above average performance for whatever you have been dealt, you have to combine expertises beyond "standard care". I read these articles early on:
Life Extension Foundation's intro to CRC,
cancer surgery,
Beyond colonscopy,
Preventing surgery induced metastasis. Adding some mild drugs and carefully chosen, extra potent supplements totally changed our situation, inexpensively.