Non-small cell lung cancer antigen 3.5ng/ml is not a serious condition, non-small cell lung cancer antigen refers to CF21-1, and the normal value is 0-3ng/mL. It includes carcinoembryonic antigen CEA, glycoconjugate protein CA12-5, cytokeratins, squamous cell antigen SCC and so on. 1. Carcinoembryonic antigen CEA: the reference value should be <5ng/mL, which is an auxiliary diagnostic index for digestive tract tumors. 2. Glycoprotein CA12-5: reference value should be <35u/mL, commonly used in the differential diagnosis of lung adenocarcinoma. 3. Cytokeratin 19: the reference value should be <3.3ng/mL, which is the preferred marker for lung squamous carcinoma. 4. Squamous cell antigen SCC: reference value should be <1.5ng/mL, commonly used in the auxiliary diagnosis of lung cancer. If patients find high antigen indexes related to non-small cell lung cancer during physical examination, there is no need to be overly nervous, and it is recommended to consult a professional physician for timely consultation and comprehensive determination through chest CT, chest X-ray, chest PET-CT and other examinations.