Types of cancer

Types of cancer

Cancer cells within a tumor are the descendants of a single cell, even after it has metastasized. Hence, a cancer can be classified by the type of cell in which it originates and by the location of the cell.
Carcinomas originate in epithelial cells (e.g. the digestive tract or glands). Hematological malignancies, such as leukemia and lymphoma, arise from cells of hematopoeitic origin, such as blood and bone marrow. Sarcoma arises from connective tissue, bone or muscle. Malignant tumors usually end in suffix "-carcinoma" for epithelial cancers, and "-sarcomas" for connective tissue tumors. Otherwise, benign tumors of both origins are denoted as "-omas." For instance, benign tumor of fat cells are known as "lipoma," while its malignant form is known as "liposarcoma."
Adult cancersIn the USA and other developed countries, cancer is presently responsible for about 25% of all deaths[1]. On a yearly basis, 0.5% of the population is diagnosed with cancer.
For adult males in the United States, the most common cancers are prostate cancer (33% of all cancer cases), lung cancer (13%), colorectal cancer (10%), bladder cancer (7%) and cutaneous melanoma (5%). As a cause of death lung cancer is the most common (31%) cause, followed by prostate cancer (10%), colorectal cancer (10%), pancreatic cancer (5%) and leukemia (4%)[1].
For adult females in the United States, breast cancer is the most common cancer (32% of all cancer cases) followed by lung cancer (12%), colorectal cancer (11%), endometrial cancer (6%, uterus) and non-Hodgkin's lymphoma (4%). By cause of death, lung cancer is again the most common (27% of all cancer deaths), followed by breast cancer (15%), colorectal cancer (10%), ovarian cancer (6%) and pancreatic cancer (6%)[1].
These statistics vary substantially in other countries.
Other cancers not mentioned:
Epithelial tumors: skin cancer (this is in fact the most common cancer but often not classified as such in health statistics), cervical cancer, anal carcinoma, esophageal cancer, hepatocellular carcinoma (in the liver), laryngeal cancer, renal cell carcinoma (in the kidneys), stomach cancer, many testicular cancers, and thyroid cancer. Hematological malignancies (blood and bone marrow): leukemia, lymphoma, multiple myeloma. Sarcomas: osteosarcoma (in bone), chondrosarcoma (arising from cartilage), rhabdomyosarcoma (in muscle) Miscellaneous origin: brain tumors, gastrointestinal stromal tumors (GIST), mesothelioma (in the pleura or pericardium), thymoma and teratomas, melanoma
Childhood cancersCancer can also occur in young children and adolescents. Here, the aberrant genetic processes that fail to safeguard against the clonal proliferation of cells with unregulated growth potential occur early in life and can progress quickly.
The age of peak incidence of cancer in children occurs during the first year of life. Leukemia (usually ALL) is the most common infant malignancy (30%), followed by the central nervous system cancers and neuroblastoma. The remainder consists of Wilms' tumor, lymphomas, rhabdomyosarcoma (arising from muscle), retinoblastoma, osteosarcoma and Ewing's sarcoma[1].
Female infants and male infants have essentially the same overall cancer incidence rates, but white infants have substantially higher cancer rates than black infants for most cancer types. Relative survival for infants is very good for neuroblastoma, Wilms' tumor and retinoblastoma, and fairly good (80%) for leukemia, but not for most other types of cancer.
Causes and pathophysiologyMain article: Carcinogenesis
Origins of cancerCell division (proliferation) is a physiological process that occurs in almost all tissues and under many circumstances. Normally the balance between proliferation and cell death is tightly regulated to ensure the integrity of organs and tissues. Mutations in DNA that lead to cancer disrupt these orderly processes.
The uncontrolled and often rapid proliferation of cells can lead to either a benign tumor or a malignant tumor (cancer). Benign tumors do not spread to other parts of the body or invade other tissues, and they are rarely a threat to life unless they extrinsically compress vital structures. Malignant tumors can invade other organs, spread to distant locations (metastasize) and become life-threatening.