Namely, cancer cells change to a more advanced stage by progressively repeating EMT and MET, without metastasis to distant sites, through the following steps: (1) epithelial cancer cells (corresponding to p-SAS) turn into mesenchymal-like cancer cells (corresponding to SAS-m4) via induction of EMT (e.g., addition of TGF-β1); (2) mesenchymal-like cancer cells turn into advanced epithelial (aE) cancer cells (corresponding to SAS-δ) via induction of MET (e.g., depletion of TGF-β1); and (3) aE cancer cells turn into advanced mesenchymal-like (aM) cancer cells via induction of secondary EMT. This evidence concerns the gene TGFB1 and cancer.