Cancer is a disease of the body cells. When normal cells lose their ability to limit and direct their growth, they divide too rapidly and grow without any order. Then, too much tissue is produced, and tumors form. Often, surgery is used to remove the cancer cells, but chemotherapy and radiation are also used.
Radiation is the use of radiation in the treatment of diseases, such as cancer. It is also called irradiation, radiotherapy, teletherapy, and brachytherapy. About 50 percent of cancer patients receive radiation therapy, either alone, or with chemotherapy. Radiation therapy is applied to the body by implanting radioactive substances into tumors by exposing them to ionizing radiation. In order for radiation to be successful, you need a delicate balance because it damages both cancer cells and healthy cells.
Different tumors need different doses of radiation. The radiation is determined by many factors, including the radiosensitivity of a tumor. The different uses and different types of radiation include primary therapy, prophylaxis, and palliative treatment. Primary therapy is for the early-stage of cancers, including prostate cancer, thyroid cancer, and some brain tumors. Helping prevent the relapse of certain forms of leukemia, prophylaxis is used to treat tissues or organs before cancer is clinically evident. Because cancer cells are prone to spreading throughout the body, palliative treatment is used to slow down the spreading of cancer cells in the body. It also helps lessen pain, bleeding, and skin lesions. Radiation can be administered two ways. Either external beam radiation or internal radiation can be used. External beam radiation treatments are administered by machines that deliver high-energy radiation. The kind of machine differs on the type and extent of the tumor. Internal radiation, also known as brachytherapy is used for either temporary or permanent implants. Methods of using this kind of radiation include parenteral or oral administration.
A second way to treat cancer is using chemotherapy. Chemotherapy is the use of chemicals to destroy cancer cells. A major advantage of chemotherapy is its ability to treat widespread or metastatic cancer, since radiation and surgery are limited to treating cancers that only affect one area.
One major purpose in all chemotherapy agents currently used is to kill cancer cells by affecting DNA synthesis. However, each drug varies in the way this occurs within the cell. The major categories of chemotherapy agents are alkylating agents, antimetabolites, plant alkaloids, and antitumor antibiotics. Alkylating agents kill cells by directly attacking DNA and can be used in leukemia, breast cancer, prostate cancer, as well as others. An example of a commonly used agent of this type would be cyclophosphamide. Antimetabolites block cell growth by interfering with DNA synthesis, stopping normal development and reproduction. 6-mercaptopurine is a commonly used antimetabolite, and can be used in the treatment of leukemia, and tumors of the breast, ovary, and gastrointestinal tract. Blocking the cell division in mitosis, plant alkaloids are anti-tumor agents derived from plants. They are commonly used in acute lymphoblastic leukemia, Wilms' tumor, and cancers of the lung, breast and testes. In this group, useful agents are vincristine and vinblastine.
In treating cancer, there are many different radiation and chemotherapy types to use in different situations. Depending on which treatment is better for each situation, patients are treated.