Calcitonin is a peptide hormone that is normally secreted by thyroid C cells, but may be produced ectopically by pancreatic NETs, phaeochromocytomas, melanomas, cervical cancer, breast and colorectal cancers, and small-cell lung and other pulmonary cancers, but usually in association with other ectopically produced peptides (6). This evidence concerns the gene CALCA and colorectal cancer.