Common signaling pathways such as the cell cycle, Toll-like receptor signaling pathway, Hippo signaling pathway, MAPK signaling pathway, PPAR signaling pathway, ERBB signaling pathway, AMPK signaling pathway, ERK signaling pathway, and microenvironmental factors such as extracellular matrix proteins, transforming growth factor-β, cancer-associated fibroblasts, etc., are associated with both breast cancer and lung cancer [44,45]. Here, EGFR is linked to lung cancer.