• Web Hosting
• Guestbooks
• Hit Counter
• Forums
• Blogs
• Mailing List
• Free Web Hosting

Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue through invasion or by implantation into distant sites by metastasis. Metastasis is defined as the stage in which cancer cells are transported through the bloodstream or lymphatic system. Cancer may affect people at all ages, but risk increases with age. It is one of the leading causes of death in developed countries.There are many types of cancer. Severity of symptoms depends on the site and character of the malignancy and whether there is metastasis. A definitive diagnosis usually requires the histologic examination of tissue by a pathologist. This tissue is obtained by biopsy or surgery. Most cancers can be treated and some cured, depending on the specific type, location, and stage. Once diagnosed, cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy. As research develops, treatments are becoming more specific for the type of cancer pathology. Drugs that target specific cancers already exist for many cancers. If untreated, cancers may eventually cause illness and death, though this is not always the case.The unregulated growth that characterizes cancer is caused by damage to DNA, resulting in mutations to genes that encode for proteins controlling cell division. Many mutation events may be required to transform a normal cell into a malignant cell. These mutations can be caused by chemicals or physical agents called carcinogens, by close exposure to radioactive materials, or by certain viruses that can insert their DNA into the human genome. Mutations occur spontaneously, or are passed down generations as a result of germ line mutations.Many forms of cancer are associated with exposure to environmental factors such as tobacco smoke, radiation, alcohol and certain viruses. While some of these can be avoided, there is no known way to entirely avoid the disease, and public health and vaccina tion programs are also important on a global scale.

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 represent 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 brain cells
• Germ cell tumours: tumors derived from germ cells, normally found in the testicle and ovary
• Choriocarcinoma: malignant tumors derived from the placenta