The ovaries are two organs located in the pelvis. They are the size and shape of almonds. The ovaries are found on either side of the uterus and connected to it by the fallopian tubes.

The ovaries have two functions:

• to produce hormones that help regulate the menstrual cycle
• to produce the egg (ovum) released during each menstrual cycle

This ovum may unite with a male sperm cell to form a fetus, or it may be discarded as part of a woman's menstrual flow. At menopause, the ovaries shrink in size and stop producing ovum.

Types of Ovarian Cancer

Ovarian tumours that are malignant, or cancerous, can potentially spread (or metastasize) to other parts of the body. There are three main types of ovarian cancer: epithelial tumours, germ cell tumours and stromal tumours.

Epithelial tumours

Ovarian cancer most often develops from the abnormal growth of cells on the surface of the ovaries. These cells are called epithelial cells. Epithelial cells line the surface of most of the body's organs. When cancers develop from the abnormal growth of epithelial cells, they are called adenocarcinomas. Most ovarian cancers (85 to 90 percent) are adenocarcinomas, and tend to occur in women between the ages of 40 and 80.

Germ cell tumours

Cancers can also develop from the tissues in the centre of the ovary that produce ovum or eggs; however, these are relatively rare. About five percent of ovarian cancers are germ cell tumours. These cancers tend to occur in young girls and teenagers. With the exception of occasionally widespread metastatic disease, these cancers are highly curable.

Stromal tumours

Tumours that develop from the connective tissue that holds the ovary together and produces the female hormones estrogen and progesterone are called stromal tumours. Approximately five to seven percent of ovarian cancers are stromal tumours.

Familial Ovarian Cancer

Some ovarian cancers are associated with specific genetic mutations, which can be inherited. These inherited ovarian cancers are also usually adenocarcinomas. Familial ovarian cancers occur in individuals who have inherited specific changes (or mutations) in their BRCA1 and BRCA2 genes, as well as women with hereditary nonpolyposis colon cancer. Research suggests that mutations in these genes make cells less able to repair damage to their DNA, making uncontrolled cell growth, and cancer, more likely.

Women with mutations in their BRCA1 and BRCA2 genes are at increased risk for developing ovarian and breast cancer. A woman who is a carrier has a 15 to 45 percent chance of developing ovarian cancer. It is important to remember though that not every woman who has family members with BRCA1 or BRCA2 will have this genetic mutation, and not every case of cancer in these families results from the genetic mutation.

Non-Cancerous Ovarian Growths

Most tumours that start growing in the ovaries are benign, meaning that they are non-cancerous or non-malignant. Non-malignant growths do not spread beyond the ovaries and do not grow rapidly. The most common type of ovarian growth is called an ovarian cyst. Generally, ovarian cysts are filled with fluid, while malignant (cancerous) growths are solid. Conditions such as endometriosis and polycystic ovary syndrome can also cause cysts to grow on the ovaries. Ovarian cysts may cause abdominal discomfort and swelling, and may need to be surgically removed; however, they are not cancer.

To read more about non-cancerous ovarian cysts, visit the Ovarian Cysts Health Centre.