Rectal cancer CA199 is not necessarily elevated, it needs to depend on the staging and other conditions.
CA199 is a representative tumor marker for digestive tract tumors. Clinically, most patients with rectal cancer will have a significant increase in CA199, but a small number of patients will not have an increase in CA199, and it depends on the stage and condition of the disease.
For early stage rectal cancer patients, because of small tumor volume, CA199 secretion is small, so there will not be obvious elevation, but generally in the late stage, there will still be elevation; there are also some patients with special situation, who will not have elevation of CA199 since the onset of disease, and they can only be confirmed by other means, but this situation is relatively rare.