Cancer antigen CA199 <2 indicates that it is within the normal range, and there may not be any tumor, but we can't rely on this indicator alone to determine whether there is a tumor or not, and it needs to be combined with pathological examination. Cancer antigen CA199 belongs to glycan antigen and is a common tumor marker with normal value <37KU/L. It is commonly used in the auxiliary screening and diagnosis of digestive tract tumors with high sensitivity and specificity. Cancer antigen CA199 <2 is a normal phenomenon, suggesting that there may not be digestive tract tumors, and no special treatment is needed. However, there may be false-negative tumor markers, which can not completely exclude the possibility of tumors, and it is necessary to carry out further examinations on imaging and other tumor markers to completely exclude the possibility of tumors. It is recommended to further improve the relevant examination and regular physical examination for early detection of the disease.