Cancer of the Ovaries
Cancer of the ovaries (ovarian carcinoma) develops most often in women aged 50 to 70. This cancer eventually develops in about 1 of 70 women. It is the second most common gynecologic cancer. However, more women die of ovarian cancer than of any other gynecologic cancer.
The risk of this cancer is higher in industrialized countries because the diet tends to be high in fat. Risk is increased for women who were unable to become pregnant, who had their first child late in life, who started menstruating early, or who reached menopause late. Risk is also increased for women who have a family history of cancer of the uterus, breast, or large intestine (colon). Less than 5% of ovarian cancer cases are related to the BRCA1 gene, which is also related to breast cancer. Use of oral contraceptives significantly decreases risk.
There are many types of ovarian cancer. They develop from the many different types of cells in the ovaries. Cancers that start on the surface of the ovaries (epithelial carcinomas) account for more than 80%. Most other ovarian cancers are germ cell tumors (which start from the cells that produce eggs) and stromal cell tumors (which start in connective tissue). Germ cell tumors are much more common among women younger than 30. Sometimes cancers from other parts of the body spread to the ovaries.
Ovarian cancer can spread directly to the surrounding area and through the lymphatic system to other parts of the pelvis and abdomen. It can also spread through the bloodstream, eventually appearing in distant parts of the body, mainly the liver and lungs.
Symptoms and Diagnosis
Ovarian cancer causes the affected ovary to enlarge. In young women, enlargement of an ovary is likely to be caused by a noncancerous fluid-filled sac (cyst). However, after menopause, an enlarged ovary is often a sign of ovarian cancer.
Many women have no symptoms until the cancer is advanced. The first symptom may be vague discomfort in the lower abdomen, similar to indigestion. Other symptoms may include bloating, loss of appetite (because the stomach is compressed), gas pains, and backache. Ovarian cancer rarely causes vaginal bleeding.
Eventually, the abdomen may swell because the ovary enlarges or fluid accumulates in the abdomen. At this stage, pain in the pelvic area, anemia, and weight loss are common. Rarely, germ cell or stromal cell tumors produce estrogens, which can cause tissue in the uterine lining to grow excessively and breasts to enlarge. Or these tumors may produce male hormones (androgens), which can cause body hair to grow excessively, or hormones that resemble thyroid hormones, which can cause hyperthyroidism.
Diagnosing ovarian cancer in its early stages is difficult, because symptoms usually do not appear until the cancer is quite large or has spread beyond the ovaries and because many less serious disorders cause similar symptoms.
If doctors detect an enlarged ovary during a physical examination, they order ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI) to help distinguish an ovarian cyst from a cancerous mass. If cancer seems unlikely, doctors reexamine the woman every few months. If doctors suspect cancer or test results are unclear, the ovaries are examined using a thin, flexible viewing tube (laparoscope) inserted through a small incision just below the navel. Also, tissue samples are removed using instruments threaded through the laparoscope. In addition, blood tests are usually performed to measure levels of substances that may indicate the presence of cancer (tumor markers), such as cancer antigen 125 (CA 125). Abnormal marker levels alone do not confirm the diagnosis of cancer, but when combined with other information, they can help confirm it.
If fluid has accumulated in the abdomen, it can be drawn out (aspirated) through a needle and tested to see whether cancer cells are present.
Prognosis and Treatment
If ovarian cancer is suspected or confirmed, surgery is performed to remove the mass and to determine how far the cancer has spread (its stage). The prognosis is based on the stage (see Section 22, Chapter 252). With treatment, 70 to 100% of women with stage I cancer and 50 to 70% of those with stage II cancer are alive 5 years after diagnosis. Only 5 to 40% of women with stage III or IV cancer are alive after 5 years.
The extent of surgery depends on the type of ovarian cancer and the stage. If the cancer has not spread beyond the ovary, removal of only the affected ovary and the adjoining fallopian tube may be sufficient. When cancer has spread beyond the ovary, both ovaries and fallopian tubes and the uterus are removed, as are nearby lymph nodes and surrounding structures that the cancer typically spreads through. If a woman has stage I cancer that affects only one ovary and she wishes to become pregnant, doctors may remove only the affected ovary and fallopian tube. For more advanced cancers that have spread to other parts of the body, removing as much of the cancer as possible improves the prognosis.
After surgery, women with stage I epithelial carcinomas usually require no further treatment. For other stage I cancers or for more advanced cancers, chemotherapy may be used to destroy any small areas of cancer that may remain. Chemotherapy consists of paclitaxel combined with cisplatin or carboplatin. Most women with advanced germ cell tumors can be cured with combination chemotherapy, usually with bleomycin, etoposide, and cisplatin. Radiation therapy is rarely used.
Advanced ovarian cancer usually recurs. So after chemotherapy, doctors typically measure levels of cancer markers. If the cancer recurs, chemotherapy (using such drugs as topotecan, hexamethylmelamine, ifosfamide, doxorubicin, or etoposide) is given.
 See the sidebar What Is an Ovarian Cyst?
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