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Ovarian cancer is a cancer that begins in an ovary.〔 It results in abnormal cells that have the ability to invade or spread to other parts of the body.〔(【引用サイトリンク】url=http://www.cancer.gov/cancertopics/cancerlibrary/what-is-cancer )〕 When this process begins, symptoms may be vague or not apparent, but they become more noticeable as the cancer progresses. These symptoms may include bloating, pelvic pain, and abdominal swelling, among others.〔 Common areas to which the cancer may spread include the lining of the abdomen, lining of the bowel and bladder, lymph nodes, lungs, and liver. The risk of ovarian cancer increases in women who have ovulated more over their lifetime. This includes those who have never had children, those who begin ovulation at a younger age or reach menopause at an older age.〔 Other risk factors include hormone therapy after menopause, fertility medication, and obesity. Factors that decrease risk include hormonal birth control, tubal ligation, and breast feeding.〔 About 10% of cases are related to inherited genetic risk; women with mutations in the genes ''BRCA1'' or ''BRCA2'' have about a 50% chance of developing the disease. The most common type of ovarian cancer, comprising more than 95% of cases, is ovarian carcinoma. There are five main subtypes of ovarian carcinoma, of which high-grade serous is most common. These tumors are believed to start in the cells covering the ovaries,〔 though some may form at the Fallopian tubes. Less common types of ovarian cancer include germ cell tumors and sex cord stromal tumors.〔 A diagnosis of ovarian cancer is confirmed through a biopsy of tissue, usually removed during surgery.〔 Screening is not recommended in women who are at average risk, as evidence does not support a reduction in death and the high rate of false positive tests may lead to unneeded surgery, which is accompanied by its own risks. Those at very high risk may have their ovaries removed as a preventive measure.〔 If caught and treated in an early stage, ovarian cancer may be curable. Treatment usually includes some combination of surgery, radiation therapy, and chemotherapy. Outcomes depend on the extent of the disease and the subtype of the cancer present.〔 The overall five-year survival rate in the United States is 45%.〔(【引用サイトリンク】url=http://seer.cancer.gov/statfacts/html/ovary.html )〕 Outcomes are worse in the developing world.〔 In 2012, ovarian cancer occurred in 239,000 women and resulted in 152,000 deaths worldwide. This makes it, among women, the seventh-most common cancer and the eighth-most common cause of death from cancer. Death from ovarian cancer is more common in North America and Europe than in Africa and Asia. == Signs and symptoms == Signs and symptoms of ovarian cancer are frequently absent in early stages; even when they do exist, they may be subtle. In most cases, symptoms exist for several months before being recognized and diagnosed, or they may initially be misdiagnosed as a condition such as irritable bowel syndrome. The early stages of ovarian cancer tend to be painless unless the growing mass causes ovarian torsion.〔 Early symptoms can include bloating, abdominopelvic pain, and pain in the side. The most typical symptoms of ovarian cancer include bloating, abdominal or pelvic pain or discomfort, back pain, irregular menstruation or postmenopausal vaginal bleeding, pain or bleeding after or during sexual intercourse, difficulty eating, loss of appetite, fatigue, diarrhea, indigestion, heartburn, constipation, nausea, early satiety, and possibly urinary symptoms (including frequent urination and urgent urination); typically these symptoms are caused by a mass pressing on the other abdominopelvic organs or from metastases.〔〔〔 If these symptoms start to occur more often or more severely than usual, especially after no significant history of such symptoms, ovarian cancer should be considered.〔〔 Metastases may cause a Sister Mary Joseph nodule.〔 In adolescents or children with ovarian tumors, the presenting symptoms can include severe abdominal pain, irritation of the peritoneum, or bleeding.〔 As the cancer becomes more advanced, it can cause an accumulation of fluid in the abdomen. If the malignancy has not been diagnosed by the time it causes ascites, it is typically diagnosed shortly thereafter.〔 Advanced cancers can also cause abdominal masses, lymph node masses, or pleural effusion.〔 Ovarian cancer symptoms can vary based on the subtype.〔 Low malignant potential (LMP) tumors, also known as borderline tumors, do not cause an increase in CA125 levels and are not identifiable with an ultrasound. The typical symptoms of a LMP tumor can include abdominal distension or pelvic pain. Particularly large masses tend to be benign or borderline.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ovarian cancer」の詳細全文を読む スポンサード リンク
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