Introduction
Ovarian cancer is the fifth most common cancer among women, and it causes more deaths than any other type of female reproductive cancer.
Here are five things every woman should know about ovarian cancer.
The numbers
Ovarian cancer is a relatively rare, but deadly, cancer. The National Cancer Institute estimates 22,280 women will be diagnosed with ovarian cancer this year, and 15,500 women will die of the disease. (For comparison, the NCI estimates that 226,870 women will be diagnosed with breast cancer, and 39,510 women will die of that disease this year.)
Overall, 1 in 72 women will be diagnosed with ovarian cancer during their lifetime.
Ovarian cancer is more often diagnosed in white women than in women of other races. In the U.S., there are 13.4 cases diagnosed yearly for every 100,000 white women, 11.3 cases per 100,000 Hispanic women, and 9.8 cases per 100,000 black or Asian women.
The overall 5-year survival rate for ovarian cancer is 43.7 percent, but the survival rate varies greatly with the stage at which a woman is diagnosed. According to the NCI, 91.5 percent of patients diagnosed before the cancer has spread survive at least five years, whereas only 26.9 percent of those diagnosed after the cancer has spread to other sites in the body survive five years.
Risk factors for ovarian cancer
The single greatest risk factor for developing ovarian cancer is a family history of the disease, according to the NCI. A woman's risk of the disease triples if she has at least one first-degree relative (a mother, daughter or sister) with ovarian cancer.
One reason that risk tends to run in families is that certain families may have mutated versions of the BRCA1 and BRCA2 genes. These mutations raise a woman's risk of ovarian cancer: 15 to 40 percent of women who have a BRCA1 or BRCA2 mutation will be diagnosed with ovarian cancer over the course of their lifetime, whereas 1.4 percent of women in the general population will be diagnosed. Women with BRCA1 or BRCA2 mutations typically develop ovarian cancer before age 50.
Still, 85 to 90 percent of ovarian cancer cases have no clear genetic link.
Fertility drugs, hormone replacement therapy after menopause, and obesity have also been linked with an increased risk of the disease. In general, a woman's risk of the disease rises with age.
Ovulation and ovarian cancer
A woman's risk of ovarian cancer seems to increase with the number of times over her life that she ovulates.
During ovulation, an egg is released from an ovary and swept into a fallopian tube — and recent research suggests that the fluid released from the ovary along with the egg contains growth factors and other molecules that damage the DNA of the nearby fallopian tube cells, said Dr. Ronny Drapkin, an assistant professor of pathology at Harvard Medical School. Furthermore, the evidence shows that the deadliest ovarian cancers, called high-grade serous cancers, actually begin when the cells at the ends of the fallopian tubes, not cells in the ovaries themselves, turn cancerous.
These findings explain the long-held observation that anything that lowers the number of times a woman ovulates also lowers her ovarian cancer risk, Drapkin said. Pregnancy, breast-feeding and birth control pills all temporarily halt ovulation, and studies have linked all of those factors to a decreased risk of ovarian cancer.
Symptoms
One of the reasons ovarian cancer is difficult to detect in its early states is that its symptoms are similar to those of other, more-common conditions, such digestive problems, according to the Mayo Clinic.
Here are some symptoms of ovarian cancer:
- Abdominal pressure, fullness or bloating
- Pelvic discomfort or pain
- Persistent indigestion, gas or nausea
- Changes in bladder or bowel habits, such as constipation or a frequent need to urinate
- Loss of appetite or quickly feeling full
- Increased abdominal girth or clothes fitting tighter around your waist
- A persistent lack of energy
In ovarian cancer, symptoms tend to last longer and worsen over time.
Because of the general commonness of the symptoms, researchers have looked to identify the frequency, severity and duration of symptoms typically associated with ovarian cancer, as opposed to other ailments. In one study, published in 2004 in the Journal of the American Medical Association, researchers compared women visiting a health clinic who didn't have ovarian cancer with those who did.
They found that the combination of abdominal pain, pelvic pain, bloating, constipation and increased abdominal size were significantly more severe in women with ovarian cancer. For example, 43 percent of women with ovarian cancer had a combination of bloating, increased abdominal size and urinary symptoms, but only 8 percent of women without the cancer had those symptoms.
Screening tests
No screening test has proved to be effective in detecting ovarian cancer. Pelvic exams conducted by doctors may include a check of the ovaries, but these often don't catch tumors until they have grown large.
Transvaginal ultrasounds, and blood tests that measure the levels of a molecule called CA-125, have been tried, but too often, these tests have not been accurate enough to consistently find cancer.
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