Ovarian cancers

ALSO KNOWN AS: Cancer of the ovaries

RELATED CONDITIONS: Abdominal cancer, colon cancer, cancer of the diaphragm, lymphatic cancer, peritoneal cancer, stomach cancer

DEFINITION: Ovarian cancers result from the development of a malignant tumor in the ovaries and can be divided into three main types. The most common is epithelial ovarian cancer, which originates in the surface cells of an ovary. The second type, germ-cell ovarian cancer, starts in the interior cells of an ovary, where eggs are produced. A third main type, stomal ovarian cancer, begins in the connective tissue cells that hold an ovary together and generate the female hormones estrogen and progesterone.

Risk factors: One of the most important risk factors involved in the development of ovarian cancers is inherited gene mutations. The National Cancer Institute (NCI) reported that the inheritance of mutated breast cancer genes, BRCA1 and BRCA2, is responsible for approximately 20 percent of all ovarian cancers. Between 45 to 50 percent of women with the BRCA1 mutation and 125 to 30 percent of women with the BRCA2 mutation will develop ovarian cancer.

Other risk factors include having had breast or colon cancer, having a family history of ovarian cancer, not having given birth, taking fertility drugs, and using hormone replacement therapy after menopause. Age is an important risk factor. According to the American Cancer Society (ACS), about half of the women diagnosed with ovarian cancer are over sixty-three. ACS also stated that the cancer is more prevalent among White women than Black American women.

Etiology and the disease process: The exact cause of ovarian cancers is unknown. Some specialists suggest that ovarian cancer in younger women is related to the tissue-repair process after ovulation. The formation and division of new cells at the site where an egg is released through a small ovarian follicular tear may produce genetic errors. Other specialists posit the origin of ovarian cancers in younger women is related to the production of abnormal cells associated with the increased hormone levels that occur before and after ovulation.

Ovarian cancers are classified according to the histology of the tumor. About 85 to 90 percent of all cases of malignant ovarian tumors are epithelial ovarian cancers, which are classified by cell type and graded from 1 to 3. Cancers that are similar to epithelial ovarian cancers include primary peritoneal carcinoma and fallopian tube cancer. The ACS estimates that 3 percent of US women diagnosed with ovarian cancers have germ-cell tumors, which develop in the egg-producing cells of the ovary and generally occur in younger women. Estimated by the Mayo Clinic to account for about 7 percent of all ovarian cancers are ovarian stromal tumors, which develop in the tissue that holds the ovary together.

Ovarian cancer cells metastasize by spreading into the naturally occurring fluids in the abdominal cavity. These cells frequently become implanted in other peritoneal structures, particularly the uterus, the intestines, the omentum, and the urinary bladder. New tumor growths often occur in these areas. In rare instances, ovarian cancer cells spread through the bloodstream or lymphatic system to other parts of the body.

Incidence: Ovarian cancer is one of the most common cancers and a leading cause of cancer-related deaths in women. About 20,000 individuals are diagnosed with ovarian cancer, and 12,500 die from the disease each year. Ovarian cancers are most common in industrialized nations. Globally, women have a one in eighty-seven chance of being diagnosed with ovarian cancer and a one in 130 chance of dying from it.

Symptoms: In most cases, ovarian cancer produces no symptoms or only mild symptoms until it progresses to an advanced stage. Symptoms include general abdominal discomfort, such as bloating, cramps, pressure, and swelling; nausea, diarrhea, or constipation; frequent urination; loss of appetite or feeling bloated after a light meal; and loss or gain of weight for no apparent reason. Other symptoms can include fatigue, back pain, pain during sexual intercourse, abnormal bleeding from the vagina, menstrual irregularities, shortness of breath, and fluid around the lungs.

Screening and diagnosis: A medical doctor evaluates a patient’s medical and family history and performs a thorough physical examination of the pelvic region. The presence of any abnormal growths should be investigated using ultrasound imaging and computed tomography (CT) scans. Ultrasound can detect differences between healthy tissues, fluid-filled cysts, and tumors. CT scans produce detailed cross-sectional images of the body. In some cases, X-rays of the colon and rectum following a barium enema help identify the presence of ovarian cancers. The level of cancer 125 (CA 125) should be assessed with a blood test. The amount of other cancer-related proteins in the blood, like HE4, also helps in diagnosing ovarian cancers.

A biopsy must be performed for a definitive diagnosis of ovarian cancer. Biopsies are usually done on tumors removed during surgery, although sometimes they are done during a laparoscopy or using a needle guided by ultrasound or CT scans. If ovarian cancer is present, the stage of the disease is assessed. Staging for ovarian cancer is as follows:

• Stage I: The cancer is limited to one or both ovaries.
• Stage II: The cancer has extended into the pelvic region, such as the uterus or fallopian tubes.
• Stage III: The cancer has spread outside the pelvis or is limited to the pelvic region but is present in the small intestine, lymph nodes, or omentum.
• Stage IV: The cancer has metastasized to the liver or tissues outside of the peritoneal cavity.

These stages are further broken down into levels of seriousness from A to C.

Treatment and therapy: Depending on the stage of ovarian cancer, surgery is often performed to remove the ovaries, uterine tubes, uterus, omentum, and associated lymph nodes. This process is referred to as surgical debulking. The stage of the disease determines whether additional therapy is needed. Typically, chemotherapy is employed, and if the cancer is localized, radiation therapy is sometimes used. The most effective chemotherapy drugs used in treating ovarian cancers are carboplatin and paclitaxel (Taxol), administered intravenously. The combination reduces cell division in ovarian tumors.

Intraperitoneal therapy, or pumping chemotherapy drugs directly into a patient’s abdomen, extends the lives of people with ovarian cancer by an additional year or more. However, it can cause side effects such as stomach pain, numbness in the extremities, and possible infection. In January 2006, the National Cancer Institute recommended an individualized combination of intravenous and intraperitoneal therapy for ovarian cancer patients. New chemotherapy drugs, vaccines, gene therapy, and immunotherapy treatments are being explored as options for treating ovarian cancers.

Prognosis, prevention, and outcomes: More than 60 percent of ovarian cancer patients are in stage III or IV at the time of diagnosis, so the prognosis is not promising. Ovarian cancer patients have an overall five-year survival rate of 50 percent, though rates vary depending on the stage and specific type of ovarian cancer, as well as other factors. With early diagnosis, aggressive surgery, and chemotherapy, the five-year survival rate is 89 to 95 percent, and the long-term survival rate approaches 75 percent. For germ-cell ovarian cancer, the prognosis is better than for epithelial ovarian cancer, with the ACS estimating the five-year survival rate at 90 percent overall.

Eating well, exercising, and managing stress help produce good overall health and reduce the risk of developing ovarian cancers. Measures that help prevent ovarian cancer include having children and breastfeeding them, using oral contraceptives (35 percent risk reduction when used for five to nine years), and having a tubal ligation. For women who have a high risk of developing ovarian cancers, removal of the ovaries may be the best prevention.

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