Transcription factor 7‐like 2 (TCF7L2), also called TCF4, affects tumour development because TCF7L2 plays a key role in the Wnt/β‐catenin signalling pathway.35 The Wnt/β‐catenin signalling pathway promotes cell proliferation and stem cell self‐renewal.36 Activation of the Wnt/β‐catenin signalling pathway maintains stemness of breast cancer cells.37 Thus, TCF7L2 mediates cell proliferation and stemness of breast cancer cells via the Wnt/β‐catenin signalling pathway.23 This evidence concerns the gene TCF7L2 and breast cancer.