Cancer (part IV)

Cancers
are classified by the type of cell that resembles the tumor and, therefore, the tissue presumed to be the origin of the tumor. The following general categories are usually accepted:
• Carcinoma: malignant tumors derived from epithelial cells. This group represents the most common cancers, including the common forms of breast, prostate, lung and colon cancer.
• Lymphoma and Leukemia: malignant tumors derived from blood and bone marrow cells
• Sarcoma: malignant tumors derived from connective tissue, or mesenchymal cells
• Mesothelioma: tumors derived from the mesothelial cells lining the peritoneum and the pleura.
• Glioma: tumors derived from glia, the most common type of brain cell
• Germinoma: tumors derived from germ cells, normally found in the testicle and ovary
• Choriocarcinoma: malignant tumors derived from the placenta
Malignant tumors are usually named using the Latin or Greek root of the organ as a prefix and the above category name as the suffix. For instance, a malignant tumor of liver cells is called hepatocarcinoma; a malignant tumor of the fat cells is called liposarcoma. For common cancers, the English organ name is used. For instance, the most common type of breast cancer is called ductal carcinoma of the breast or mammary ductal carcinoma. Here, the adjective ductal refers to the appearance of the cancer under the microscope, resembling normal breast ducts.
Benign tumors are named using -oma as a suffix with the organ name as the root. For instance, a benign tumor of the smooth muscle of the uterus is called leiomyoma (the common name of this frequent tumor is fibroid).
Adult cancers
In the USA and other developed countries, cancer is presently responsible for about 25% of all deaths.[3] On a yearly basis, 0.5% of the population is diagnosed with cancer.
The statistics below are for adults in the United States, and will vary substantially in other countries:

Childhood cancers
Cancer can also occur in young children and adolescents, but it is rare. Some studies have concluded that pediatric cancers, especially leukemia, are on an upward trend.[4][5]
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.[3]
Female 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.