The present invention relates a pharmaceutical composition comprising an EGFR inhibitor and methylene-tetrahydrofolate, tetrahydrofolate or methyl-tetrahydrofolate, for use in the treatment of cancer. The methylene-tetrahydrofolate, tetrahydrofolate or methyl-tetrahydrofolate enhances the anticancer efficacy of the EGFR inhibitor. The cancers that may be treated include breast cancer, gastric cancer, gastrointestinal cancer, gall bladder cancer, bile duct cancer, colon cancer, rectal cancer, liver cancer, pancreatic cancer, head and neck cancer, esophageal cancer, mesothelioma cancer, lung cancer including non-small-cell lung cancer, ovarian cancer, endometrial cancer, cervical cancer, peripheral T-cell lymphoma (PTCL), melanoma, brain tumors, adenocarcinoma, esophageal cancer, and osteosarcoma
