Page 15 Complete Your CE Test Online - Click Here TYPES OF CANCER Cancers are typically named for the organs or tissues where the cancers form. For example, lung cancer starts in cells of the lung, and brain cancer starts in cells of the brain. Cancers also may be described by the type of cell that formed them, such as an epithelial cell or a squamous cell. Cell-specific types of cancer These are the most common types of cancer by cell type. This is the terminology that is found on pathology reports and can be used to help patients understand these reports. Carcinoma Carcinomas are the most common type of cancer. They are formed by epithelial cells, which cover the inside and outside surfaces of the body. Epithelial cells often have a column-like shape when viewed under a microscope, but there are many types of epithelial cells. Carcinomas that begin in different epithelial cell types have even more- specific names: ● ● Adenocarcinoma is a cancer that forms in glandular epithelial cells, which produce fluids or mucus. Most cancers of the breast, colon, and prostate are adenocarcinomas. ● ● Basal cell carcinoma is a cancer that begins in the lower or basal layer of the epidermis. ● ● Squamous cell carcinoma is a cancer that forms in squamous cells, epithelial cells that lie just beneath the outer surface of the skin. Squamous cells are also found in organs like the stomach, intestines, lungs, bladder, and kidneys. Squamous cells look flat, like fish scales, when viewed under a microscope. Squamous cell carcinomas may also be called epidermoid carcinomas. ● ● Transitional cell carcinoma is a cancer that forms in a type of epithelial tissue called transitional epithelium, or urothelium. This tissue, which is made up of many layers of epithelial cells that can get bigger and smaller, is found in the linings of the bladder, ureters, the renal pelvis, and a few other organs. Some cancers of the bladder, ureters, and kidneys are transitional cell carcinomas. Sarcoma Sarcomas are cancers that form in bone and soft tissues, including muscle, fat, blood vessels, lymph vessels, and fibrous tissue, such as tendons and ligaments. Soft tissue sarcoma forms in soft tissues of the body, including muscle; tendons; fat blood vessels; lymph vessels; nerves; fibrous tissues, such as tendons and ligaments; and the tissue around joints. The most common types of soft tissue sarcoma are leiomyosarcoma, Kaposi’s sarcoma, malignant fibrous histiocytoma, liposarcoma, and dermatofibrosarcoma protuberans. Leukemia Cancers that begin in the blood-forming tissue of the bone marrow are called leukemias. Large numbers of abnormal white blood cells (leukemia cells and leukemic blast cells) proliferate in the blood and bone marrow, crowding out normal blood cells. Low numbers of normal blood cells can result in anemia, thrombocytopenia, and leukopenia, which can cause fatigue, hypoxia, abnormal bleeding, and an increased risk of infection. There are four common types of leukemia, which are grouped based on how the speed of disease progression (acute or chronic) and on the type of hematopoietic cell the cancer starts in (lymphoblastic or myeloid). Osteosarcoma is the most common cancer of bone. Lymphoma Lymphoma is cancer that begins in T lymphocytes or B lymphocytes (commonly called T cells and B cells). These white blood cells normally help fight infection and are part of the immune system. In lymphoma, abnormal lymphocytes build up in lymph nodes, lymph 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 that are called Reed-Sternberg cells. These lymphocytes usually originate from B cells. 2. Non-Hodgkin lymphoma: This is a large group of cancers that start in lymphocytes. The cancers can grow quickly or slowly and can originate from B cells or T cells. Multiple myeloma Multiple myeloma begins in plasma cells, another type of immune cell. The abnormal plasma cells, called myeloma cells, crowd the bone marrow and form tumors in bones all through the body. Multiple myeloma is also called plasma cell myeloma and Kahler disease. Melanoma Melanoma is cancer that begins in cells that become melanocytes, which are specialized cells that make melanin (the pigment that gives skin its color). Most melanomas form on the skin, but melanomas can also form in other pigmented tissues, such as the eye. They can also form under the nails and more rarely on mucous membranes in the mouth or genital and perianal areas. Brain and spinal cord tumors There are different types of brain and spinal cord tumors. These tumors are named based on the type of cell in which they formed and where the tumor first formed in the central nervous system. For example, an astrocytic tumor begins in star-shaped brain cells called astrocytes, which help keep nerve cells healthy. Brain tumors can be benign or malignant, but any that continue to grow can be life-threatening. Following are some less common cellular-based cancer types: ● ● Germ cell tumors: Germ cell tumors begin in the cells that normally give rise to sperm or eggs in the testes or ovaries. These tumors can occur almost anywhere in the body (because germ cells can develop in other parts of the body), although extragonadal germ cell tumors happen most often in the pineal gland, mediastinum, or retroperitoneum. They can be either benign teratomas or malignant (seminomas and nonseminomas). ● ● Neuroendocrine tumors: Neuroendocrine tumors arise from cells that release hormones into the blood in response to a signal from the nervous system. These tumors, which may make higher-than- normal amounts of hormones, can cause many different symptoms. Neuroendocrine tumors may be benign or malignant. ● ● Carcinoid tumors: Carcinoid tumors are a type of neuroendocrine tumor. These slow-growing tumors are usually found in the gastrointestinal system (most often in the rectum and small intestine). Carcinoid tumors may spread to the liver or other sites in the body, and they may secrete substances such as serotonin or prostaglandins, causing carcinoid syndrome. Carcinoid syndrome occurs in about 10% of people with these tumors, and depending on where it is and where it has spread can cause such symptoms as flushing of the face, usually without sweating; abdominal pain or cramping; diarrhea; wheezing or dyspnea; and tachycardia. These symptoms, especially the flushing and diarrhea, may be triggered or exacerbated by stress, alcohol, or foods containing tyramine (such as aged cheeses or pickled meats). Carcinoids that affect the small intestine can also cause nausea, vomiting, jaundice, dyspepsia, and bloating. Signs and symptoms of cancer Certain cancers are visible almost from the beginning. Skin cancer and melanomas, for example, are often found by the patient. As with most cancers, early intervention increases the chance of survival and decreases the risk of complications of treatment. Typically, very early cancers do not cause pain or other noticeable symptoms. Patients often take pain more seriously than other symptoms, and they should be encouraged to see their primary care providers if they have a kind of pain that is new to them, especially if it persists. Cancer can cause pain, along with many other different kinds of signs and symptoms. What the patient is likely to notice in the way of symptoms depends on what type of cancer it is, how advanced it is, and where it is located in the body (see the subsection “Does metastatic cancer have symptoms?” in the section “How does cancer spread?”).