Ovarian cancer is a cancerous growth arising from different parts of the ovary.
The most common form of ovarian cancer (≥80%) arises from the outer lining (epithelium) of the ovary.. However, recent evidence shows cells that line the Fallopian tube (epithelium) also to be prone to develop into the same kind of cancer as seen in the ovaries. Since the ovaries and tubes are closely related to each other, it is hypothesized that these cells can mimic ovarian cancer. Other forms arise from the egg cells (germ cell tumor).
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.
Signs and symptoms
These symptoms include:
> Pelvic or abdominal pain
> Pain in the back or legs
> Diarrhea, gas, nausea, constipation, indigestion
> Difficulty eating or feeling full quickly
> Urinary symptoms (urgency or frequency)
> Pain during sex
> Abnormal vaginal bleeding
> Trouble breathing
Women with ovarian cancer report that symptoms are persistent and represent a change from normal for their bodies. The frequency and/or number of such symptoms are key factors in the diagnosis of ovarian cancer. Several studies show that even early stage ovarian cancer can produce these symptoms. Women who have these symptoms almost daily for more than a few weeks should see their doctor, preferably a gynecologist. Prompt medical evaluation may lead to detection at the earliest possible stage of the disease. Early stage diagnosis is associated with an improved prognosis.
Several other symptoms have been commonly reported by women with ovarian cancer. These symptoms include fatigue, indigestion, back pain, pain with intercourse, constipation and menstrual irregularities. However, these other symptoms are not as useful in identifying ovarian cancer because they are also found in equal frequency in women in the general population who do not have ovarian cancer.
- The exact cause is usually unknown. The risk of developing ovarian cancer appears to be affected by several factors. 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. Ovarian cancer is reduced in women after tubal ligation.
The relationship between use of oral contraceptives and ovarian cancer was shown in a summary of results of 45 case-control and prospective studies. Cumulatively these studies show a protective effect for ovarian cancers. Women who used oral contraceptives for 10 years had about a 60% reduction in risk of ovarian cancer. (risk ratio .42 with statistical significant confidence intervals given the large study size, not unexpected). This means that if 250 women took oral contraceptives for 10 years, 1 ovarian cancer would be prevented. This is by far the largest epidemiological study to date on this subject (45 studies, over 20,000 women with ovarian cancer and about 80,000 controls).
There is good evidence that in some women genetic factors are important. Carriers of certain mutations of the BRCA1 or the BRCA2 gene are notably at risk. The BRCA1 and BRCA2 genes account for 5%-13% of ovarian cancers and certain populations (e.g. Ashkenazi Jewish women) are at a higher risk of both breast cancer and ovarian cancer, often at an earlier age than the general population.Patients with a personal history of breast cancer or a family history of breast and/or ovarian cancer, especially if diagnosed at a young age, may have an elevated risk.
A pooled analysis of ten (10) prospective cohort studies conducted in a number of countries and including 529,638 women found that neither total alcohol consumption nor alcohol from drinking beer, wine or spirits was associated with ovarian cancer risk.” The results of a case-control study in the region of Milan, Italy, “suggests that relatively elevated alcohol intake (of the order of 40 g per day or more) may cause a modest increase of epithelial ovarian cancer risk”. “Associations were also found between alcohol consumption and cancers of the ovary and prostate, but only for 50 g and 100 g a day.” “Statistically significant increases in risk also existed for cancers of the stomach, colon, rectum, liver, female breast, and ovaries.”
Stage I – limited to one or both ovaries
> IA – involves one ovary; capsule intact; no tumor on ovarian surface; no malignant cells in ascites or peritoneal washings
> IB – involvs both ovaries; capsule intact; no tumor on ovarian surface; negative washings
> IC – tumor limited to ovaries with any of the following: capsule ruptured, tumor on ovarian surface, positive washings
Stage II – pelvic extension or implants
> IIA – extension or implants onto uterus or fallopian tube; negative washings
> IIB – extension or implants onto other pelvic structures; negative washings
> IIC – pelvic extension or implants with positive peritoneal washings
Stage III – microscopic peritoneal implants outside of the pelvis; or limited to the pelvis with extension to the small bowel or omentum
> IIIA – microscopic peritoneal metastases beyond pelvis
> IIIB – macroscopic peritoneal metastases beyond pelvis less than 2 cm in size
> IIIC – peritoneal metastases beyond pelvis > 2 cm or lymph node metastases
- Stage IV – distant metastases to the liver or outside the peritoneal cavity
- 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 advanced disease a combination of surgical reduction with a combination 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.
Ovarian cancer usually has a poor prognosis. It is disproportionately deadly because it lacks any clear early detection or screening test, meaning that most cases are not diagnosed until they have reached advanced stages. More than 60% of patients presenting with this cancer already have stage III or stage IV cancer, when it has already spread beyond the ovaries. Ovarian cancers shed cells into the naturally occurring fluid within the abdominal cavity. These cells can implant on other abdominal (peritoneal) structures, included the uterus, urinary bladder, bowel and the lining of the bowel wall (omentum). These cells can begin forming new tumor growths before cancer is even suspected.