Nien et al. suggest that, in the case of elevated CEA values in “routine” biochemical testing, further investigation should focus not only on upper and lower gastrointestinal endoscopy to rule out evidence of gastrointestinal malignancy, but also on neck ultrasound and measuring serum calcitoninto find a possible MTC. This evidence concerns the gene CEACAM5 and medullary thyroid gland carcinoma.