Cancer

Cancer is a class of diseases characterized by uncontrolled cell division and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue (invasion) or by migration of cells to distant sites (metastasis). This unregulated growth is caused by damage to DNA, resulting in mutations to vital genes that control cell division, among other functions. One or more of these mutations, which can be inherited or acquired, can lead to uncontrolled cell division and tumor formation. Tumor ("swelling" in Latin) refers to any abnormal mass of tissue, but may be either malignant (cancerous) or benign (noncancerous). Only malignant tumors are capable of invading other tissues or metastasizing.

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.

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Carcinomas originate in epithelial cells (e.g. the digestive tract or glands). Hematological malignancies, such as leukemia and lymphoma, arise from blood and bone marrow. Sarcoma arises from connective tissue, bone or muscle. Melanoma arises in melanocytes. Teratoma begins within germ cells.

Related Topics:
Carcinoma - Epithelial cell - Digestive tract - Gland - Hematological malignancies - Leukemia - Lymphoma - Blood - Bone marrow - Sarcoma - Connective tissue - Bone - Muscle - Melanoma - Melanocyte - Teratoma - Germ cell

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Adult cancers

In the USA and other developed countries, cancer is presently responsible for about 25% of all deaths{{fn|1}}. On a yearly basis, 0.5% of the population is diagnosed with cancer.

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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%){{fn|1}}.

Related Topics:
United States - Prostate cancer - Lung cancer - Colorectal cancer - Bladder cancer - Melanoma - Pancreatic cancer

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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%){{fn|1}}.

Related Topics:
United States - Breast cancer - Endometrial cancer - Non-Hodgkin's lymphoma - Ovarian cancer

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These statistics vary substantially in other countries.

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Other cancers not mentioned:

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• 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 cancers

Cancer 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.

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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{{fn|1}}.

Related Topics:
Leukemia - ALL - Neuroblastoma - Wilms' tumor - Lymphoma - Rhabdomyosarcoma - Retinoblastoma - Osteosarcoma - Ewing's sarcoma

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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.

Related Topics:
Wilms' tumor - Retinoblastoma

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