CEACAM5 and neoplasm: However, low-dose biotin intake (up to 10 mg) can interfere with immunoassays, including those used for tumor markers essential for monitoring and follow-up, such as Cancer Antigen 125 (CA 125), Cancer Antigen 15–3 (CA 15–3), and Carcinoembryonic Antigen (CEA) [35,63,64].