Ovarian cancer is a type of cancer that begins in the ovaries. Women have two ovaries, one on each side of the uterus. The ovaries -- each about the size of an almond -- produce eggs (ova) as well as the hormones estrogen, progesterone and testosterone.

Ovarian cancer is a cancerous growth arising from the ovary. Symptoms are frequently very subtle early on and may include: bloating, pelvic pain, difficulty eating and frequent urination, and are easily confused with other illnesses. Ovarian cancer often goes undetected until it has spread within the pelvis and abdomen. At this late stage, ovarian cancer is difficult to treat and is often fatal.

Most (more than 90%) ovarian cancers are classified as epithelial and are believed to arise from the surface (epithelium) of the ovary. However, some evidence suggests that the fallopian tube could also be the source of some ovarian cancers. Since the ovaries and tubes are closely related to each other, it is thought that these fallopian cancer cells can mimic ovarian cancer. Other types may arise from the egg cells (germ cell tumor) or supporting cells. These cancers are grouped into the category of gynecologic cancer. In the United States each year 82,000 women are diagnosed with gynecologic cancer.

Signs and symptoms of ovarian cancer are frequently absent early on and when they exist they may be subtle. In most cases, the symptoms persist for several months before being recognized and diagnosed. Most women with ovarian cancer report one or more symptoms such as abdominal pain or discomfort, an abdominal mass, bloating, back pain, urinary urgency, constipation, tiredness and a range of other non-specific symptoms, as well as more specific symptoms such as pelvic pain, abnormal vaginal bleeding or involuntary weight loss. There can be a build-up of fluid in the abdominal cavity.

In most cases, the exact cause of ovarian cancer remains unknown. The risk of developing ovarian cancer appears to be affected by several factors. Older women, and in those who have a first or second degree relative with the disease, have an increased risk. Hereditary forms of ovarian cancer can be caused by mutations in specific genes. Infertile women and those with a condition called endometriosis, those who have never been pregnant and those who use postmenopausal estrogen replacement therapy are at increased risk. Use of combined oral contraceptive pills is a protective factor. The more children a woman has, the lower her risk of ovarian cancer. Early age at first pregnancy, older age of final pregnancy and the use of low dose hormonal contraception have also been shown to have a protective effect. The risk is also lower in women who have had their fallopian tubes blocked surgically.

Ovarian cancer treatments are available. Researchers are studying ways to improve ovarian cancer treatment and looking into ways to detect ovarian cancer at an earlier stage -- when a cure is more likely. Treatment usually involves chemotherapy and surgery, and sometimes radiotherapy.

Surgical treatment may be sufficient for malignant tumors that are well-differentiated and confined to the ovary. Addition of chemotherapy may be required for more aggressive tumors that are confined to the ovary. For patients with an advanced form of the disease, a combination of surgical reduction with a chemotherapy regimen is standard. Borderline tumors, even following spread outside of the ovary, are managed well with surgery, and chemotherapy is not seen as useful.

Surgery is the preferred treatment and is frequently necessary to obtain a tissue specimen for differential diagnosis via its histology. Surgery performed by a specialist in gynecologic oncology usually results in an improved result. Improved survival is attributed to more accurate staging of the disease and a higher rate of aggressive surgical excision of tumor in the abdomen by gynecologic oncologists as opposed to general gynecologists and general surgeons.

The type of surgery depends upon how widespread the cancer is when diagnosed, as well as the presumed type and grade of cancer. The surgeon may remove one or both ovaries, the fallopian tubes, and the uterus. For some very early tumors, only the involved ovary and fallopian tube will be removed,especially in young females who wish to preserve their fertility.

In advanced malignancy, where complete resection is not feasible, as much tumor as possible is removed. In cases where this type of surgery is successful, the prognosis is improved compared to patients where large tumor masses are left behind. Minimally invasive surgical techniques may facilitate the safe removal of very large tumors with fewer complications of surgery.

Chemotherapy has been a general standard of care for ovarian cancer for decades, although with highly variable protocols. Chemotherapy is used after surgery to treat any residual disease, if appropriate. This depends on the histology of the tumor; some kinds of tumor are not sensitive to chemotherapy. In some cases, there may be reason to perform chemotherapy first, followed by surgery.

Radiation therapy is not effective for advanced stages because when vital organs are in the radiation field, a high dose cannot be safely delivered. Radiation therapy is then commonly avoided in such stages as the vital organs may not be able to withstand the problems associated with these ovarian cancer treatments.

Adopted from wikipedia.com and mayoclinic.com