Serum carcinoembryonic antigen (CEA) is elevated in various malignancies (e.g., colorectal cancer, medullary thyroid cancer, lung cancer, breast cancer, mucinous ovarian cancer, etc.), and CEA screening is part of various national and international surveillance guidelines.[296] A large number of aptamer‐based sensors have been developed over the past decade, targeting sensitive and specific detection of CEA.[297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307] For example, Shu et al. This evidence concerns the gene CEACAM5 and medullary thyroid gland carcinoma.