Body CO2 lvl comparison

between normal person and cancer patient.

Unfortunately for this topic, the 2 words cancer and CO2 have too many other connections in this context to be search-engine friendly enough to yield out any relevant result.

Anyone knows an article/paper or two concerning this topic?

Body CO2?

lol wut?

Blood CO2 lvl to be more precise.

Probably negligible, if the person has any degree of acid base regulation of the blood.  CO₂ dissolves in water to form a buffer solution of carbonic acid.  This is regulated by various other body chemicals, along with breathing.

TL;DR holding your breath has a bigger effect