The results from these datasets prompt several important conclusions: (1) the activation of C/T genes can be an early event during tumorigenesis, detectable within in situ tumors, (2) the type of C/T genes activated in a tumor is consistent between early and later-stage tumors, indicating there is no switch in expression, and (3) HORMAD1 and CT83 prove to be the most promising markers due to their association with the most deadly subtype of breast cancer and their robust pattern of expression (RNA and protein) in tumor cells detected at the single-cell level. This evidence concerns the gene CT83 and breast cancer.