Cancers are classified by the kind of cell that resembles the growth and, therefore, the tissue presumed to become the origin of the growth. These are the histology and also the location, respectively. Examples of common categories include:
- Carcinoma: Malignant tumors based on epithelial cells. This group represents the most typical cancers, including the common types of breast, prostate, lung and intestinal tract cancer.
- Sarcoma: Malignant tumors based on connective tissue, or mesenchymal tissue.
- Lymphoma and leukemia: Malignancies based on hematopoietic (blood-forming) tissue
- Germ cell tumor: Tumors based on totipotent cells. In adults usually found in the testicle as well as ovary; in fetuses, babies, and young children most often on the body midline, particularly at the end of the tailbone; in horses usually found at the poll (base from the skull).
- Blastic tumor or even blastoma: A tumor (generally malignant) which resembles a good immature or embryonic tissue. Several tumors are most common within children.