<P> Cancers are classified by the type of cell that the tumor cells resemble and is therefore presumed to be the origin of the tumor . These types include: </P> <Ul> <Li> Carcinoma: Cancers derived from epithelial cells . This group includes many of the most common cancers and include nearly all those in the breast, prostate, lung, pancreas and colon . </Li> <Li> Sarcoma: Cancers arising from connective tissue (i.e. bone, cartilage, fat, nerve), each of which develops from cells originating in mesenchymal cells outside the bone marrow . </Li> <Li> Lymphoma and leukemia: These two classes arise from hematopoietic (blood - forming) cells that leave the marrow and tend to mature in the lymph nodes and blood, respectively . </Li> <Li> Germ cell tumor: Cancers derived from pluripotent cells, most often presenting in the testicle or the ovary (seminoma and dysgerminoma, respectively). </Li> <Li> Blastoma: Cancers derived from immature "precursor" cells or embryonic tissue . </Li> </Ul> <Li> Carcinoma: Cancers derived from epithelial cells . This group includes many of the most common cancers and include nearly all those in the breast, prostate, lung, pancreas and colon . </Li> <Li> Sarcoma: Cancers arising from connective tissue (i.e. bone, cartilage, fat, nerve), each of which develops from cells originating in mesenchymal cells outside the bone marrow . </Li>

Cancers that arise in epithelial tissue are termed