Most ovarian cancers (85-90%) develop from the cells that cover the outer surface of the ovary, called the epithelial cells. The cells that make up epithelial ovarian cancers have several histologic patterns, which are recognised under the microscope. They are referred to as serous, mucinous, endometrioid or clear cell types. Some lack distinctive features and may be considered "undifferentiated" epithelial tumours.
Ten to fifteen percent of ovarian cancers develop in the germ cells or sex cord stromal cells of the ovary. Ovarian germ cell tumours develop from the cells that produce the ova or eggs. Germ cell tumours may occur in teenagers and in women in their twenties. However, overall, these are rare tumours and have a good prognosis.
Ovarian stromal tumours develop from connective tissue cells that hold the ovary together and produce the female hormones oestrogen and progesterone. These tumours are generally much less aggressive than the other tumours. These are also rare tumours.
What are the symptoms of ovarian cancer?
There are usually no obvious symptoms of ovarian cancer. Women complain about vague symptoms including abdominal swelling or bloating, generalised abdominal discomfort, early satiety, lack of appetite, dyspepsia, malaise, urinary frequency or weight change (either gain or loss). Women may develop unexplained ascites (fluid in the abdominal cavity) which contributes to the abdominal discomfort. Because the symptoms are not unique to ovarian cancer, the disease can be difficult to identify and diagnose.
Ovarian cancer diagnosis
A definitive diagnosis of ovarian cancer requires surgery. The initial surgery has two aims. First, to remove any cancer that exists (or as much as possible), including removing the ovaries, the uterus and the omentum. The best results for survival are in those women in whom all the cancer can be removed. Second, to sample tissues and surrounding nodes to determine where the tumour has spread (to determine the stage of the disease).
In pre-menopausal women, a more limited surgery may be appropriate depending upon the cell type of the tumour.
What are the treatment options for ovarian cancer?
After the initial diagnosis has been established at surgery, additional therapy will depend on several factors, including the histologic cell type, the stage, the extent of spread of the cancer; and the residual tumour remaining at the end of the initial surgery.
Treatment includes chemotherapy (usually a combination of drugs), or radiation. Other treatment options may include immunotherapy, or in the future, gene therapy.
What are the risk factors for ovarian cancer?
The causes of ovarian cancer are unknown. The disease tends to be more common in women from western industrialised countries, especially Caucasian women, who have had no full-term pregnancies. There also have been noted associations with exposure to talc or asbestos. In addition, there is an association with infertility.
It appears that factors that decrease ovulation have been associated with a lower risk of ovarian cancer in the general population. Women who have had multiple pregnancies or who have breast-fed have fewer ovulations and have been noted to have a decrease in the occurrence of ovarian cancer. The use of oral contraceptives has also been associated with a decrease in the development of ovarian cancer. The protection provided by oral contraceptives appears to be real and increases as the duration of the pill use increases. A risk reduction of up to 60% may occur when oral contraceptives are used for longer than five years. Recent studies have noted that there is a decreased incidence of ovarian cancer in women with a history of tubal ligation. The mechanism of this is unclear. The use of powders
containing talc should be avoided on the external female genitals.
Is ovarian cancer hereditary?
Most of ovarian cancers are sporadic and not inherited. However, 5-10% of individuals who develop ovarian cancer have an inherited genetic susceptibility to the disease. Generally, the risk of developing ovarian cancer increases as the number of family members affected by ovarian cancer increases. Having a first-degree relative affected by ovarian cancer (for example, a mother or a sister) increases a woman’s lifetime risk from 1.4% to 3.1%. Those at greatest risk for inherited genetic susceptibility have a personal or family history of ovarian and/or breast cancer. Histories that include cancers with early age of onset, multiple primary (new) cancers and Jewish ancestry reflect greater risk.
There are three different syndromes that fall under the heading of familial ovarian cancer. The first, is a site-specific, hereditary ovarian cancer syndrome in which only ovarian cancer is manifested. More commonly, however, there is the hereditary breast-ovarian cancer syndrome in which both ovarian cancer and breast cancer may occur in the same family. And finally, there is the Lynch II syndrome in which breast, ovarian, colon, endometrial and other cancers occur throughout the family. The cases of familial ovarian cancer, however, account again for only 5-10% of ovarian cancers.
Those people who are interested in learning more about their hereditary risks should speak to their physicians about the option of genetic counselling and testing.
What can I do to prevent ovarian cancer?
There are no known methods to guarantee prevention of ovarian cancer. Women who are diagnosed in an early stage, however, have a higher survival rate. Unfortunately, ovarian cancer is usually not diagnosed at an early stage. There are no effective methods currently for diagnosing ovarian cancer early in all women and thus intervening at an early stage. Currently, there are many programs attempting to develop strategies for diagnosing ovarian cancer early.
Can I get ovarian cancer if I have my ovaries removed?
Women at a very high risk of developing ovarian cancer can consider removal of the ovaries. Such a "prophylactic" removal of the ovaries appears to lower the risk of developing ovarian cancer, but does not eliminate the risk. Women with one first-degree relative with ovarian cancer have a risk of developing the disease, which is approximately 3.1%. A prophylactic oophorectomy (removal of the ovaries) as an independent operation is not recommended, in general, for these women. With two first-degree relatives, the risk of developing ovarian cancer is approximately 7% and a prophylactic removal of the ovaries may be considered. In general, women found to be carriers or who have a family history highly suggestive of a syndrome may be appropriate candidates for prophylactic removal of the ovaries.
Removal of the ovaries results in lost hormone production, which can have side effects. A woman considering prophylactive removal of the ovaries should discuss possible side effects with her doctor.