There are more than 100 types of cancer in the world. The type of cancer is usually named according to the organ or tissue that forms the cancer. For example, lung cancer originates in lung cells and brain tumors originate in brain cells. Cancers can also be classified by the type of cells that form them, such as epithelial or squamous cell carcinoma. The following are some classifications of cancers that originate from specific cell types: Carcinoma: Carcinomas are the most common type of cancer. They are formed by epithelial cells, which are cells that cover the internal organs of the body and the surface of the skin. Many types of epithelial cells exist in the body, and under the microscope epithelial cells are usually columnar in shape. Cancers that originate from different epithelial cell types have specific names: 1. Adenocarcinoma originates from epithelial cells that produce body fluids or mucus. The tissue formed by this type of epithelial cell is sometimes called a gland. For example, most cancers that occur in the breast, colon and prostate are adenocarcinomas. 2. Basal cell carcinoma is a cancer that originates in the subepidermal or basal layer, which is the outer layer of human skin. 3. Squamous cell carcinoma originates from squamous cells, which are epithelial cells located under the outer surface of the skin. Squamous cells also grow in many other organs, including the stomach, intestines, lungs, bladder and kidneys. Under the microscope, squamous cells are flattened like fish scales. Squamous cell carcinoma is sometimes called epidermoid carcinoma. 4.Migratory cell carcinoma occurs in the epithelial tissue of the migratory epithelium or urethra-cyst epithelium. This epithelial tissue formed by multiple layers of epithelial cells that can change size is present in the bladder, ureter, kidney (renal pelvis), and other organs. Some cancers that occur in the bladder, ureter and kidney are metastatic cell carcinomas. Sarcomas: Sarcomas are cancers that occur in bone and soft tissues, which include muscle, fat, blood vessels, lymphatic vessels and fibrous tissues (such as tendons and ligaments). The most common bone tumor is osteosarcoma. The most common soft tissue sarcomas are smooth muscle sarcoma, Kaposi’s sarcoma, malignant fibrous histiocytoma, liposarcoma and aneurysmal dermatofibrosarcoma. Soft tissue sarcomas form in the soft tissues of the body, which include muscles, tendons, fat, blood vessels, lymphatic vessels, nerves and tissues surrounding joints. Soft tissue sarcomas are cancers that occur in the soft tissues of the body, including muscles, tendons, fat, lymphatic vessels, blood vessels, nerves, and tissues surrounding joints. Tumors can be found anywhere in the body, but usually occur in the arms, legs, chest or abdomen. Signs of soft tissue sarcoma include the formation of a mass in the soft tissue or swelling of the soft tissue. Sometimes, the signs or symptoms do not develop until the tumor is large enough to compress peripheral nerves or other areas. Soft tissue sarcomas can be seen in children and adults. Treatment is usually more effective in children, and children have a better chance of being cured than adults. There are different types of soft tissue sarcomas based on the type of cells that form them. Different types should be given different treatments. 1. Rhabdomyosarcoma is the most common type of soft tissue sarcoma in children, and it occurs in the muscles that attach to the bones and help the body move. Most rhabdomyosarcomas are diagnosed in children under 10 years of age. Rhabdomyosarcoma usually forms a mass on the adjacent body surface and is easily detected early. 2. Gastrointestinal mesenchymal tumors are soft tissue sarcomas that form in the soft tissues of the gastrointestinal tract, usually in the stomach or small intestine. It is most common in adults and can be benign (not cancerous) or malignant (cancerous). Mesenchymal tumors of the gastrointestinal tract are usually asymptomatic in their early stages. 3. Ewing sarcoma, Kaposi’s sarcoma and uterine sarcoma are other types of soft tissue sarcomas. Radiation therapy, certain diseases and genetic disorders can increase the risk of developing soft tissue sarcoma. Leukemia: Cancers that occur in the blood-forming tissue of the bone marrow are called leukemias, which do not form solid tumors. Instead, large numbers of abnormal white blood cells (leukemia cells and leukemia mother cells) accumulate in the blood and bone marrow, squeezing out normal blood cells. The low-functioning blood cells have difficulty oxygenating the body, controlling bleeding and fighting off infections. There are four common types of leukemia, which are grouped based on the rate of disease progression (acute or chronic) and the type of blood cells (lymphoblastoid or bone marrow) from which the cancer originates. Leukemia is a cancer that occurs in the blood cells. Most blood cells are formed in the bone marrow. In leukemia, immature blood cells become cancerous, and these cells fail to function as they should and also squeeze out healthy blood-forming cells in the bone marrow. The different types of leukemia depend on the type of blood cells that become cancerous. For example, lymphocytic leukemia is a cancer that occurs in lymphoblastoid cells (white blood cells – cells whose function is to fight off infection). Leukocytes are the most common blood cells to develop blood tumors. But red blood cells (cells that carry oxygen from lung tissue to the rest of the body) and platelets (cells that clot blood) can also develop cancer. Leukemia is most common in adults over age 55, but it is also the most common cancer in children under age 15. Leukemia can be acute or chronic. Acute leukemia is a fast-growing cancer that usually deteriorates rapidly. Chronic leukemia is a slower growing cancer that slowly worsens over time. The treatment and prognosis for leukemia depends on the type of blood cells affected and whether the leukemia is acute or chronic. Lymphoma: Lymphomas are cancers that originate from lymphocytes (T or B cells). These are the white blood cells that fight disease as part of the immune system. In lymphoma, abnormal lymphocytes accumulate in the lymph nodes and lymphatic vessels and other organs of the body. There are two main types of lymphoma: 1. Hodgkin’s lymphoma: People with this disease have abnormal lymphocytes, called Reed-Sternberg cells, which are usually formed by B cells. 2. Non-Hodgkin’s lymphoma: Includes a large group of cancers that originate from lymphocytes. The cancer is formed by B or T cells and can grow rapidly or slowly. Lymphomas are cancers that originate from cells of the lymphatic system. The lymphatic system is part of the immune system, which helps the body fight infection and disease. Because lymphatic tissue is found throughout the body, lymphoma can occur in almost any part of the body. The two main types of lymphoma include Hodgkin’s lymphoma and non-Hodgkin’s lymphoma (NHL). NHL can be seen in children and adults. Most people with Hodgkin’s lymphoma have the classic features in which large abnormal lymphocytes (a type of white blood cell) are present in lymph nodes called R-S cells. Hodgkin’s lymphoma is usually curable. Different types of leukocytes (B cells, T cells, NK cells) form many different types of NHL. most types of NHL originate from B cells. nhl can appear inert (slow growing) or aggressive (fast growing). The most common types of NHL in adults are diffuse large B-cell lymphoma (usually aggressive) and follicular lymphoma (usually inert). Mycosis fungoides and Sézary’s syndrome are two types of NHL that originate from leukocytes in the skin. Primary central nervous system lymphoma originating from leukocytes in the brain, cremaster or eye is a rare type of NHL. Treatment and chances of cure depend on the stage and type of lymphoma. Multiple myeloma: Multiple myeloma originates from plasma cells, which are another type of immune cell. Abnormal plasma cells, known as myeloma cells, make up the bone marrow and form bone tumors throughout the body. Multiple myeloma is also known as plasma cell myeloma and Kahler’s disease. Plasma cells are the cells in the immune system that produce antibodies that help the body fight infections and diseases. A plasma cell tumor is a buildup of abnormal plasma cells in the bone marrow, resulting in the production of large amounts of antibodies to the M protein in the bone marrow, which can lead to thickening of the blood and damage to the kidneys. Abnormal plasma cells can also form tumors in bone or soft tissue. When only one tumor is present in the body, the disease is called plasmacytoma. When multiple tumors are present, the disease is called multiple myeloma. Both are malignant (cancerous). When you have multiple myeloma, you may not show signs or symptoms for a long time, until the disease progresses. Myeloma tumors can weaken bones, cause excess calcium in the blood, and damage the kidneys and other organs. Bone pain is a common symptom of advanced multiple myeloma. Other signs and symptoms include frequent infections, anemia, bleeding, numbness, tingling, and weakness. Monoclonal immunoglobulinemia uncharacterized (MGUS) is a benign (non-cancerous) plasmacytoma. MGUS is characterized by low levels of M protein and does not present with physical symptoms or injury. In rare cases, MGUS can become multiple myeloma. Melanoma: Melanoma originates from melanocytes, which are characterized by the production of melanin (which gives skin its color). Most melanomas grow on the skin, but melanomas can also form in other colored tissues such as the eyes. Skin cancer: The skin protects us from heat and protects us from sun damage, other injuries and infections. The skin also helps control body temperature and stores water and fat. Skin cancer is the most common type of cancer and it usually occurs on sun-exposed skin, but can occur anywhere in the body. Skin is made up of several layers, and skin cancer begins in the epidermis (outer layer), which is made up of squamous cells, basal cells and melanocytes. There are different types of skin cancer; squamous cell and basal cell skin cancers are sometimes referred to as non-melanoma skin cancers. Non-melanoma skin cancers usually respond to treatment and rarely metastasize to other parts of the body. Melanoma is more aggressive than most other types of skin cancer. If not diagnosed early, melanoma is likely to invade adjacent tissues and spread to other parts of the body. The number of cases of melanoma is increasing each year, and although melanoma accounts for only 2% of all skin cancers, most skin cancers result in death from melanoma. Rare types of skin cancer include Merkel cell carcinoma, cutaneous lymphoma, and Kaposi’s sarcoma. Intraocular melanoma: Intraocular melanoma is a rare disease in which tumors form in the melanocytes of the eye, the cells that produce melanin (which gives skin and eyes their color). Intraocular melanoma grows on the uvea (the pigmented layer of the eye). The uvea is divided into three parts; the iris, the colored area at the front of the eye, the ciliary body, a ring of muscle tissue that changes the size of the pupil and the shape of the lens, and the choroid, the layer of blood vessels that brings oxygen and nutrients to the eye. Most intraocular melanomas begin to grow in the choroid. Intraocular melanoma may have no early signs or symptoms and is sometimes detected only by an eye exam. Risk factors for intraocular melanoma include having fair skin – freckles that are noticeable and burn easily, not tanning easily, and having blue, green or other light-colored eyes. Brain and cremaster tumors: There are different types of brain and cremaster tumors, which are named according to the type of cells from which they form and the location in the central nervous system where the tumor first appears. For example, astrocytomas originate within astrocytic brain cells called astrocytes, which are cells that help keep nerve cells healthy. Brain tumors can be benign (not cancerous) or malignant (cancerous). Other types of tumors: Germ cell tumors Germ cell tumors are tumors that originate from sperm or egg cells. These tumors can occur almost anywhere in the body and can be benign or malignant. Neuroendocrine tumors Neuroendocrine tumors originate from cells that release hormones into the bloodstream, and the released hormones act as nerve signals in response. (Neuroendocrine tumors are tumors that originate from neuroendocrine cells.) These tumors may produce higher than normal amounts of hormones, resulting in many different symptoms. Neuroendocrine tumors can be benign or malignant. Examples of neuroendocrine tumors include carcinoid tumors, islet cell tumors, medullary thyroid carcinoma, pheochromocytoma, cutaneous neuroendocrine carcinoma (Merkel cell carcinoma), small cell lung cancer, and large cell neuroendocrine carcinoma. Carcinoid tumors are neuroendocrine tumors that usually grow slowly in the gastrointestinal system (most commonly in the rectum and small intestine). Carcinoid tumors may spread to the liver or other parts of the body and may secrete substances such as blood