People are not unfamiliar with cancer, basically they talk about it, but not many of them really know about it. There are more than 100 types of cancer, including breast cancer, skin cancer, lung cancer, colon cancer, prostate cancer, lymphoma, etc. The specific symptoms vary greatly depending on the tumor, and cancer treatment can include surgery, chemotherapy, radiation therapy, etc. Cancer begins when healthy cells in our body divide and replace themselves in a controlled manner, but when the cells are altered in some way so that they proliferate out of control, a tumor is a mass made up of such abnormal clusters of cells. Most cancers form tumors, but not all tumors are cancerous. Benign or non-cancerous tumors do not spread to other parts of the body or create new tumors. Malignant or cancerous tumors crowd out healthy cells, interfere with body functions, and absorb nutrients from body tissues. Cancer is the process of spreading or metastasizing directly so that malignant cells pass through lymphatic vessels or blood vessels and eventually form new tumors in other parts of the body. The main types of cancer are carcinoma, sarcoma, melanoma, lymphoma, and leukemia. Among these, common cancers originate in the skin, lungs, breast, pancreas, and other organs and glands. Lymphoma is a cancer formed by the malignant transformation of lymphocytes. Leukemia is a cancer formed by the malignant transformation of blood cells; it does not usually form a solid tumor. Sarcomas are cancers that develop as a result of malignant changes in bone, muscle, fat, blood vessels, cartilage or other soft or connective tissues of the body and occur at a relatively reduced rate. Melanoma is a cancer that arises from the malignant transformation of pigment-forming cells in the skin.