Ovarian cancer is a cancerous growth arising from different parts of the ovary.
Most (>90%) ovarian cancers are classified as "epithelial" and were believed to arise from the surface (epithelium) of the ovary.
However, recent 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 hypothesized that these cells can mimic ovarian cancer.
Other types arise from the egg cells (germ cell tumor) or supporting cells (sex cord/stromal).
In 2004, in the United States, 25,580 new cases were diagnosed and 16,090 women died of ovarian cancer.
The risk increases with age and decreases with pregnancy.
Lifetime risk is about 1.6%, but women with affected first-degree relatives have a 5% risk.
Women with a mutated BRCA1 or BRCA2 gene carry a risk between 25% and 60% depending on the specific mutation.
Ovarian cancer is the fifth leading cause of death from cancer in women and the leading cause of death from gynecological cancer.
In early stages ovarian cancer is associated with abdominal distension.
10-year relative survival ranges from 84.1% in stage IA to 10.4% in stage IIIC.
Ovarian cancer causes non-specific symptoms.
Early diagnosis would result in better survival, on the assumption that stage I and II cancers progress to stage III and IV cancers (but this has not been proven).
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 (ascites) in the abdominal cavity.
Diagnosis of ovarian cancer starts with a physical examination (including a pelvic examination), a blood test (for CA-125 and sometimes other markers), and transvaginal ultrasound.
The diagnosis must be confirmed with surgery to inspect the abdominal cavity, take biopsies (tissue samples for microscopic analysis) and look for cancer cells in the abdominal fluid.
Treatment usually involves chemotherapy and surgery, and sometimes radiotherapy.
In most cases, the cause of ovarian cancer remains unknown.
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 (most notably BRCA1 and BRCA2, but also in genes for hereditary nonpolyposis colorectal cancer).
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 risk is also lower in women who have had their uterine tubes blocked surgically (tubal ligation).