卵巢癌-Ovarian Cancer(Cancer of the Ovary)

What are the ovaries?

Women have two ovaries, one on either side of the uterus (womb) in the lower abdomen. Ovaries are small and round, each about the size of a walnut. The ovaries make eggs. In fertile women, each month an egg (ovum) is released from one of the ovaries. The egg passes down the fallopian tube into the uterus where it may be fertilised by a sperm.

The ovaries also make hormones including the main 'female' hormones - oestrogen and progesterone. These hormones pass into the bloodstream and have various effects on other parts of the body including regulating the menstrual cycle and periods.

What is cancer?

Cancer is a disease of the cells in the body. The body is made up from millions of tiny cells. There are many different types of cell in the body, and there are many different types of cancer which arise from different types of cell. What all types of cancer have in common is that the cancer cells are abnormal and multiply 'out of control'.

A malignant tumour is a 'lump' or 'growth' of tissue made up from cancer cells which continue to multiply. Malignant tumours invade into nearby tissues and organs which can cause damage.

Malignant tumours may also spread to other parts of the body. This happens if some cells break off from the first (primary) tumour and are carried in the bloodstream or lymph channels to other parts of the body. These small groups of cells may then multiply to form 'secondary' tumours (metastases) in one or more parts of the body. These secondary tumours may then grow, invade and damage nearby tissues, and spread again.

Some cancers are more serious than others, some are more easily treated than others (particularly if diagnosed at an early stage), some have a better outlook (prognosis) than others.

So, cancer is not just one condition. In each case it is important to know exactly what type of cancer has developed, how large it has become, and whether it has spread. This will enable you to get reliable information on treatment options and outlook. See separate leaflet called 'What are Cancer and Tumours' for further details about cancer in general.

What is ovarian cancer?

There are various types of ovarian cancer. They are classified by the type of cell from which the cancer originates.

• Epithelial ovarian cancer is the most common type (about 9 in 10 cases). This type of cancer develops from one of the cells that surrounds the outside of each ovary. (This outer layer of cells is called the germinal epithelium of the ovary.) Epithelial ovarian cancer mainly affects women who have had their menopause - usually women aged over 50. It is rare in younger women. There are various 'sub-types' depending on the exact look of the cells causing the cancer (which can be seen under the microscope).
• Germ cell ovarian cancer develops from germ cells (the cells that make the eggs). About 1 in 10 cases of ovarian cancer are germ cell cancers. They typically develop in younger women. Again, there are various 'sub-types' depending on the exact look of the cells causing the cancer. Most cases of germ cell ovarian cancer are curable, even if diagnosed at a late stage, as it usually responds well to treatment.
• Stromal ovarian cancer develops from connective tissue cells (the cells that fill the ovary and produce hormones). This type of cancer is rare.

The treatments and outlook (prognosis) are different for each of the above types of ovarian cancer.

The rest of this leaflet only discusses the common epithelial ovarian cancer.

What causes (epithelial) ovarian cancer?

A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply 'out of control'. (See separate leaflet called 'What Causes Cancer' for more details.)

In most cases an ovarian cancer occurs for no apparent reason. However, there are factors which are known to increase the risk of ovarian cancer developing. These include the following.

• Age. Most cases occur in women over the age of 50 years.
• Ovulation factors. Things which affect the number of times a woman ovulates in her life seem to slightly alter the risk. For example, taking the contraceptive pill, having children, and breast feeding seems to slightly lower the risk (as these factors reduce the number of times a woman will ovulate). Not having children and having a late menopause seems to slightly increase the risk.
• Infertility (or drugs used to promote ovulation in the treatment of infertility) may be linked to a small increased risk.
• Taking HRT (hormone replacement therapy) may slightly increase the risk.
• Regular use of talc in the genital region may possibly increase the risk slightly.
• Previous radiation of the pelvic area may increase the risk.
• A tubal tie (sterilisation) or hysterectomy (removal of the uterus) may reduce the risk slightly.

Family history and genetic testing
Most cases of ovarian cancer are not due to genetic or hereditary factors. In a small number of cases, a 'faulty gene' which can be inherited may trigger ovarian cancer to develop. If you have inherited a 'faulty gene' your risk of developing ovarian cancer increases quite a lot, and it often develops at a younger age than usual. Some women are referred for genetic testing if a faulty gene is suspected on the basis of a strong family history of cancer. For example, if you have two or more close relatives who have had ovarian or breast cancer, (or certain other cancers), you may benefit from genetic testing. (Certain faulty genes which may trigger cancer can cause different types of cancer.)

Research is underway to see if screening women who carry a faulty gene will detect ovarian cancer early (when treatment is most likely to be curative). Screening tests being studied are the C125 blood test and regular ultrasound scan of the ovary (see below). For further details see 'further information' at the end of this leaflet.醫(yī)學(xué)全在線www.med126.com

What are the symptoms of (epithelial) ovarian cancer?

In most cases, no symptoms develop for quite some time after the cancer has first developed. Symptoms may only be noticed when the tumour has become quite large, or has spread. In some cases, an early symptom is a change in the normal pattern of periods (menstrual irregularity).

As the tumour grows symptoms which may develop include:

• Pain or a feeling of 'pressure' in the lower abdomen.
• A feeling of bloating in the abdomen.
• Pain in the lower abdomen when having sex.
• Passing urine frequently (as the bladder is 'irritated' by the nearby tumour).
• Change in bowel habit such as constipation or diarrhoea.
• Ascites. This is a collection of fluid in the abdomen which can cause your abdomen to swell. It is caused by growth and spread of the cancer to the inside of the abdomen which causes fluid to accumulate.

All of the above symptoms can be caused by various other conditions. Also, when symptoms first start they are often 'vague' for some time such as mild discomfort in the lower abdomen. These symptoms may be thought to be due to other things, and so the diagnosis of ovarian cancer may not be considered for some time until the symptoms get worse.

If the cancer spreads to other parts of the body, various other symptoms can develop.

How is (epithelial) ovarian cancer diagnosed and assessed?

Initial tests
Initial tests to diagnose ovarian cancer may include

• A vaginal examination by a doctor. He or she may feel an enlarged ovary or other suspicious abnormality.
• An ultrasound scan. This is a safe and painless test which uses sound waves to create images of organs and structures inside your body. The probe of the scanner may be placed on your abdomen to scan the ovaries. A small probe is also commonly placed inside the vagina to scan the ovaries from this angle.
• A blood test. A sample of blood can detect a protein called CA-125. The level is high in more than 8 in 10 women with advanced ovarian cancer, and in about half of women with early ovarian cancer. Other non-cancerous conditions can also cause a high level. So this test does not conclusively diagnose or rule out ovarian cancer, but a high level can be a helpful test.

Further tests
You may be advised to have further tests depending on the symptoms you have and the results of the initial tests. These tests can help to confirm the diagnosis, and to stage the disease. The aim of staging is to find out:

• How much the tumour has grown, and whether it has grown to other nearby structures such as the uterus, bladder or rectum.
• Whether the cancer has spread to local lymph glands (nodes).
• Whether the cancer has spread to other areas of the body (metastasised).

Further tests may include one or more of the following:

• CT scan or MRI scan of the lower abdomen. These scans can provide detail of the structure of the internal organs. (See separate leaflets for each of these tests.)
• A chest x-ray to assess your general health and to check if the cancer has spread to your lungs.
• Blood tests to assess your general health and to check if the cancer has affected the function of your liver or kidneys.
• Tests to check out the bowel or urinary tract. For example, colonoscopy, barium enema, or intravenous urogram. (See separate leaflets for each of these tests.) These tests are more likely to be needed if you have symptoms such as constipation or urinary frequency which may indicate the cancer has spread to these areas.
• Aspiration of fluid. If your abdomen has swollen with fluid then a sample can be taken. This is done by numbing a small area of skin on the abdomen with local anaesthetic. Then a fine needle is pushed through the abdominal wall and some fluid can be drawn into an attached syringe. The sample is looked at under the microscope to look for cancer cells.
• Laparoscopy. This is a procedure to look inside your abdomen by using a laparoscope. A laparoscope is like a thin telescope with a light source. It is used to light up and magnify the structures inside the abdomen. A laparoscope is passed into the abdomen through a small incision (cut) in the skin. The ovaries and other internal organs can be seen and biopsies (small samples) can be taken to be looked at under the microscope to detect and confirm cancer cells.

Even with the above tests, the exact stage (extent of spread) may not be known until after an operation to treat the cancer.

Grading of the cancer cells
If a biopsy of the cancer is taken, or cancer cells are found in aspirated fluid, the cells can assessed. By looking at certain features of the cells under the microscope the cancer can be 'graded'.

• Grade 1 (low grade) - the cells look reasonably similar to normal ovarian cells. The cancer cells are said to be 'well differentiated'. The cancer cells tend to grow and multiply quite slowly and are not so 'aggressive'.
• Grade 2 - is a middle grade.
• Grade 3 - the cells look very abnormal and are said to be 'poorly differentiated'. The cancer cells tend to grow and multiply quite quickly and are more 'aggressive'.

Finding out the stage and grade of the cancer helps doctors to advise on the best treatment options. It also gives a reasonable indication of outlook (prognosis). See separate leaflet called 'Cancer Staging and Grading' for details.

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