Ovarian Cancer

The ovaries

The ovaries are two small, oval-shaped organs that are part of the female reproductive system. They are in the lower part of the tummy (abdomen), which is known as the pelvis. Other organs are very close to the ovaries (see diagrams below). These include:

The ureters, which drain urine from the kidneys to the bladder. The bladder.
The back passage (rectum).
The lower part of the small bowel.
The omentum (a membrane which surrounds all of the pelvic and abdominal organs and keeps them in place). It is also called the peritoneum.
Groups of lymph nodes.

Each month, in women of childbearing age, one of the ovaries produces an egg. The egg passes down the fallopian tube to the womb (uterus). If the egg is not fertilised by a sperm it passes out of the womb and is shed, along with the lining of the womb, as part of the monthly period.

The ovaries also produce the female sex hormones, oestrogen and progesterone. As a woman nears the menopause („change of life') the ovaries make less of these hormones and periods gradually stop.

The ovaries and their surrounding structures

Side view of the abdomen showing the peritoneum surrounding the abdominal organs

What is cancer?

The organs and tissues of the body are made up of tiny building blocks called cells. Cancer is a disease of these cells.

Cells in different parts of the body may look and work differently but most reproduce themselves in the same way. Cells are constantly becoming old and dying, and new cells are produced to replace them. Normally, cells divide in an orderly and controlled manner. If for some reason the process gets out of control, the cells carry on dividing, developing into a lump which is called a tumour.

Tumours can be either benign or malignant. Cancer is the name given to a malignant tumour. Doctors can tell if a tumour is benign or malignant by examining a small sample of cells under a microscope. This is called a biopsy.

In a benign tumour the cells do not spread to other parts of the body and so are not cancerous. However, if they continue to grow at the original site, they may cause a problem by pressing on the surrounding organs.

A malignant tumour consists of cancer cells that have the ability to spread beyond the original area. If the tumour is left untreated, it may spread into and destroysurrounding tissue. Sometimes cells break away from the original (primary) cancer. They may spread to other organs in the body through the bloodstream or lymphatic system.

The lymphatic system is part of the immune system - the body's natural defence against infection and disease. It is a complex system made up of organs, such as bone marrow, the thymus, the spleen, and lymph nodes. The lymph nodes (or glands) throughout the body are connected by a network of tiny lymphatic ducts.

When the cancer cells reach a new area they may go on dividing and form a new tumour. This is known as a secondary cancer or metastasis.

It is important to realise that cancer is not a single disease with a single type of treatment. There are more than 200 different kinds of cancer, each with its own name and treatment.

Types of cancer

Carcinomas

The majority of cancers, about 85% (85 in a 100), are carcinomas. They start in the epithelium, which is the covering (or lining) of organs and of the body (the skin). The common forms of breast, lung, prostate and bowel cancer are all carcinomas.

Carcinomas are named after the type of epithelial cell that they started in and the part of the body that is affected. There are four different types of epithelial cells:

squamous cells - that line different parts of the body, such as the mouth, gullet (oesophagus), and the airways
adeno cells - form the lining of all the glands in the body and can be found in organs such as the stomach, ovaries, kidneys and prostate
transitional cells - are only found in the lining of the bladder and parts of the urinary system
basal cells - that are found in one of the layers of the skin.

A cancer that starts in squamous cells is called a squamous cell carcinoma. A cancer that starts in glandular cells is called an adenocarcinoma. Cancers that start in transitional cells are transitional cell carcinomas, and those that start in basal cells are basal cell carcinomas.

Leukaemias and lymphomas

These occur in the tissues where white blood cells (which fight infection in the body) are formed, i.e. the bone marrow and lymphatic system. Leukaemia and lymphoma are quite rare and make up about 6.5% (6.5 in 100) of all cancers.

Sarcomas

Sarcomas are very rare. They are a group of cancers that form in the connective or supportive tissues of the body such as muscle, bone and fatty tissue. They account for less than 1% (1 in 100) of cancers.

Sarcomas are split into two main types:

bone sarcomas - that are found in the bones
soft tissue sarcomas - that develop in the other supportive tissues of the body.

Others forms of cancer

Brain tumours and other very rare forms of cancer make up the remainder of cancers.

Types of ovarian cancer

Most ovarian cancers are a type called epithelial cancer. Epithelial ovarian cancer means the cancer has started in the cells that cover the surface of the ovary. There are several types of epithelial cancers of the ovary. The most common types are:

serous
endometrioid

Less common types of epithelial ovarian cancer are:

mucinous
clear cell
undifferentiated or unclassifiable.

They are currently all treated in a similar way.

There are also less common types of ovarian cancer. These include germ cell tumours (ovarian teratomas) and sarcomas. Germ cell tumours tend to affect younger women and behave very differently to other types of ovarian cancer.

This booklet does not cover treatment for the rarer types of ovarian cancer.