The difference between malignant tumors and cancer is that malignant tumors contain cancer within them, and cancer is a malignant tumor that occurs in epithelial tissue. Tumors are divided into benign and malignant tumors. Malignant tumors are divided into cancers and sarcomas according to the tissue from which the lesion originates. Malignant tumors originating from epithelial tissue are cancers; malignant tumors originating from mesenchymal tissue are sarcomas. Most patients often think that malignant tumors are equivalent to cancer because 85-90% of malignant tumors are cancers and 10-15% of malignant tumors are sarcomas. Cancer is a malignant tumor that occurs in epithelial tissues, including the nasal cavity, oral cavity, lungs, esophagus, gastrointestinal tract, uterus, and other organs, and malignant tumors occurring in these areas are referred to as cancer. Thus, in the definition of pathology, malignant tumors include cancer.