Cancer refers to malignant tumors. Tumors are classified into benign and malignant types, with the malignant ones commonly referred to as cancer. Often discussed are those originating from epithelial cells, termed carcinomas, such as lung cancer and breast cancer. However, there are special types such as those originating from mesenchymal tissue, called sarcomas, including synovial sarcoma and osteosarcoma, which are also malignant tumors and belong to cancer. Lymphoma, a malignant tumor originating from lymph nodes or extranodal tissues or organs, is also classified as cancer.