marți, 6 aprilie 2010
joi, 11 martie 2010
The peritoneum is made up of cells called epithelial cells. These cells also line the ovaries. Although the lining tissue in the ovaries forms only a small part of the ovaries themselves, this is where most ovarian cancers start. Ovarian cancers commonly spread from the ovaries to the peritoneum. For this reason, primary peritoneal cancer can only be diagnosed in women once ovarian cancer has been excluded.
Primary peritoneal cancer and epithelial ovarian cancer (the commonest type of ovarian cancer) behave very similarly, and are treated in the same way.
Radiation therapy (also called radiotherapy, x-ray therapy, or irradiation) is the use of a certain type of energy (called ionizing radiation) to kill cancer cells and shrink tumors. Radiation therapy injures or destroys cells in the area being treated (the “target tissue”) by damaging their genetic material, making it impossible for these cells to continue to grow and divide. Although radiation damages both cancer cells and normal cells, most normal cells can recover from the effects of radiation and function properly. The goal of radiation therapy is to damage as many cancer cells as possible, while limiting harm to nearby healthy tissue.
There are different types of radiation and different ways to deliver the radiation. For example, certain types of radiation can penetrate more deeply into the body than can others. In addition, some types of radiation can be very finely controlled to treat only a small area (an inch of tissue, for example) without damaging nearby tissues and organs. Other types of radiation are better for treating larger areas.
In some cases, the goal of radiation treatment is the complete destruction of an entire tumor. In other cases, the aim is to shrink a tumor and relieve symptoms. In either case, doctors plan treatment to spare as much healthy tissue as possible.
About half of all cancer patients receive some type of radiation therapy. Radiation therapy may be used alone or in combination with other cancer treatments, such as chemotherapy or surgery. In some cases, a patient may receive more than one type of radiation therapy.
When is radiation therapy used?
Radiation therapy may be used to treat almost every type of solid tumor, including cancers of the brain, breast, cervix, larynx, lung, pancreas, prostate, skin, spine, stomach, uterus, or soft tissue sarcomas. Radiation can also be used to treat leukemia and lymphoma (cancers of the blood-forming cells and lymphatic system, respectively). Radiation dose to each site depends on a number of factors, including the type of cancer and whether there are tissues and organs nearby that may be damaged by radiation.
For some types of cancer, radiation may be given to areas that do not have evidence of cancer. This is done to prevent cancer cells from growing in the area receiving the radiation. This technique is called prophylactic radiation therapy.
Radiation therapy also can be given to help reduce symptoms such as pain from cancer that has spread to the bones or other parts of the body. This is called palliative radiation therapy.
What is the difference between external radiation therapy, internal radiation therapy (brachytherapy), and systemic radiation therapy? When are these types used?
Radiation may come from a machine outside the body (external radiation), may be placed inside the body (internal radiation), or may use unsealed radioactive materials that go throughout the body (systemic radiation therapy). The type of radiation to be given depends on the type of cancer, its location, how far into the body the radiation will need to go, the patient's general health and medical history, whether the patient will have other types of cancer treatment, and other factors.
Most people who receive radiation therapy for cancer have external radiation. Some patients have both external and internal or systemic radiation therapy, either one after the other or at the same time.
External radiation therapy usually is given on an outpatient basis; most patients do not need to stay in the hospital. External radiation therapy is used to treat most types of cancer, including cancer of the bladder, brain, breast, cervix, larynx, lung, prostate, and vagina. In addition, external radiation may be used to relieve pain or ease other problems when cancer spreads to other parts of the body from the primary site.
Intraoperative radiation therapy (IORT) is a form of external radiation that is given during surgery. IORT is used to treat localized cancers that cannot be completely removed or that have a high risk of recurring (coming back) in nearby tissues. After all or most of the cancer is removed, one large, high-energy dose of radiation is aimed directly at the tumor site during surgery (nearby healthy tissue is protected with special shields). The patient stays in the hospital to recover from the surgery. IORT may be used in the treatment of thyroid and colorectal cancers, gynecological cancers, cancer of the small intestine, and cancer of the pancreas. It is also being studied in clinical trials (research studies) to treat some types of brain tumors and pelvic sarcomas in adults.
Prophylactic cranial irradiation (PCI) is external radiation given to the brain when the primary cancer (for example, small cell lung cancer) has a high risk of spreading to the brain.
Internal radiation therapy (also called brachytherapy) uses radiation that is placed very close to or inside the tumor. The radiation source is usually sealed in a small holder called an implant. Implants may be in the form of thin wires, plastic tubes called catheters, ribbons, capsules, or seeds. The implant is put directly into the body. Internal radiation therapy may require a hospital stay.
Internal radiation is usually delivered in one of two ways, each of which is described below. Both methods use sealed implants.
Interstitial radiation therapy is inserted into tissue at or near the tumor site. It is used to treat tumors of the head and neck, prostate, cervix, ovary, breast, and perianal and pelvic regions. Some women treated with external radiation for breast cancer receive a “booster dose” of radiation that may use interstitial radiation or external radiation.
Intracavitary or intraluminal radiation therapy is inserted into the body with an applicator. It is commonly used in the treatment of uterine cancer. Researchers are also studying these types of internal radiation therapy for other cancers, including breast, bronchial, cervical, gallbladder, oral, rectal, tracheal, uterine, and vaginal.
Systemic radiation therapy uses radioactive materials such as iodine 131 and strontium 89. The materials may be taken by mouth or injected into the body. Systemic radiation therapy is sometimes used to treat cancer of the thyroid and adult non-Hodgkin lymphoma. Researchers are investigating agents to treat other types of cancer.
Peritoneal cancer is a rare cancer that develops in the peritoneum, a thin, delicate sheet that lines the inside wall of the abdomen and covers the uterus and extends over the bladder and rectum. The peritoneum is made of epithelial cells. By producing a lubricating fluid, the peritoneum helps the organs to move smoothly inside the abdomen. Peritoneal cancer looks and behaves like ovarian cancer, but the ovaries are minimally involved. Women who develop ovarian cancer after having had their ovaries previously removed likely have peritoneal cancer.
The surface of the ovaries also is made from epithelial cells. Therefore, peritoneal cancer and the most common type of ovarian cancer, called epithelial cancer, produce some of the same symptoms and are often treated in the same way. In addition, women who are at an increased risk of developing ovarian cancer, particularly due to the BRCA1 and BRCA2 genetic mutations, also are at increased risk for peritoneum cancer.
In its earliest stages, symptoms for peritoneum cancer can be very vague and difficult to spot. Like ovarian cancer, the condition often does not produce any symptoms until late in its development. When symptoms of peritoneum cancer do develop, they are similar to those of ovarian cancer. Symptoms may include:
General abdominal discomfort and pain, such as gas, indigestion, pressure, swelling, bloating or cramps
Nausea, diarrhea, constipation and frequent urination
Loss of appetite
Feeling full even after a light meal
Weight gain or loss with no known reason
Abnormal bleeding from the vagina