Ovarian cancer

What is ovarian cancer?

Ovarian cancer is a type of cancer that originates in the ovaries. These are the female reproductive organs responsible for producing eggs, and hormones such as oestrogen and progesterone.

The ovaries are walnut-sized organs located on either side of the womb (uterus). See the separate leaflet called Gynaecological cancer to learn more about where ovaries are and what they do.

Types of 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

This is the most common type (about 9 in 10 cases). This type of cancer develops from one of the cells that surround 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 years. It is rare in younger women. There are various subtypes, depending on the exact look of the cells causing the cancer (which can be seen under the microscope).

Germ cell ovarian cancer

This type of ovarian cancer develops from germ cells (the cells that make the eggs). About 1 in 10 to 20 cases of ovarian cancer are germ cell cancers. They typically develop in younger women.

Again, there are various subtypes, 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

This 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 type of ovarian cancer.

See the separate leaflet called Cancer for more general information about cancer.

The rest of this leaflet is only about epithelial ovarian cancer.

Stages of ovarian cancer

The stages of ovarian cancer are as follows:

• Stage 1 - just involving the ovaries.

• Stage 2 - the cancer has spread outside the ovaries but not outside the pelvis.

• Stage 3 - the cancer has spread outside the pelvis but not involved other areas of the body.

• Stage 4 - the cancer has spread to other parts of the body such as the liver and lungs.

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

How common is ovarian cancer?

About 7,500 women are diagnosed with ovarian cancer every year in the UK. The majority of cases are in women aged over 50 years, although it can occur in younger women. About half of all cases occur in women aged 65 or more.

Symptoms of ovarian cancer

In many cases, no symptoms develop for quite some time after the cancer first develops. Symptoms may only be noticed when the cancerous (malignant) tumour has become quite large. As the tumour grows, the most common early symptoms include one or more of the following:

• Constant pain or a feeling of pressure in the pelvic area (lower part of the tummy or abdomen).

• Bloating in the tummy (abdomen) that does not go away (rather than bloating that comes and goes). There may also be an actual increase in size of your abdomen.

• Difficulty eating; feeling full quickly.

Other symptoms that may develop include:

• Loss of appetite.

• Weight loss.

• Back pain.

• 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.

• A more marked swelling of the abdomen. This is caused by ascites, which is a collection of fluid in the abdomen. It is caused by the growth and spread of the cancer to the inside of the abdomen, which causes fluid to accumulate.

Could it be something else?

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 conditions.

The possibility of ovarian cancer may not be considered for some time until the symptoms become worse.

In particular, one condition that is often mistaken for ovarian cancer is irritable bowel syndrome (IBS). However, it is uncommon for IBS to first develop in women over the age of 50 years.

(IBS typically first develops at a younger age - but may persist into later life.) So, if you have not had IBS-type symptoms in the past but then develop them aged over 50 years then ovarian cancer should be considered. It needs to be ruled out (usually by tests) before making a diagnosis of IBS.

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

What causes ovarian cancer?

A cancerous (malignant) 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 causes it to multiply out of control. See the separate leaflet called Causes of cancer for more details.

Risk factors for ovarian cancer

In most cases, the reason why an ovarian cancer develops is not known. However, there are factors which are known to alter the risk of ovarian cancer developing. These include:

• Age. Most cases occur in women over the age of 50 years.

• Producing an egg (ovulation). Factors that reduce the number of times a woman will ovulate slightly lower the risk. For example, taking the combined oral contraceptive (COC) pill, having children and breastfeeding. In contrast, not having children and having a late menopause slightly increase the risk.

• Being overweight or obese increases the risk.

• Taking hormone replacement therapy (HRT) may slightly increase the risk.

• A history of a condition called endometriosis slightly increases the risk.

• Sterilisation surgery or removal of the uterus (hysterectomy) appears to reduce the risk slightly.

• Genetic factors - increase the risk, see below.

Family history and genetic testing

Most cases of ovarian cancer are not due to genetic or hereditary factors. A few cases are due to faulty genes which increase the risk of cancer of the breast and ovary. Some women, trans men and non-binary people are referred for genetic testing if a faulty gene is suspected on the basis of a strong family history of certain cancers.

The most common genes are BRCA1 and BRCA2. For example, if you have two or more close relatives who have had ovarian or breast cancer at a young age (or certain other cancers), you may benefit from genetic testing. If this applies to you then it is advised that you see your GP to talk it through to establish if you should be referred for genetic testing.

In addition, if you are eligible for enhanced breast screening due to a family history of breast cancer, you should be aware of the early symptoms of ovarian cancer (see below). See a doctor promptly if you develop any of these symptoms.

How is ovarian cancer diagnosed?

If your doctor suspects you might have ovarian cancer they will refer you urgently to your local specialist - a gynaecologist. The National Institute for Health and Care Excellence (NICE) has recommended that a person should receive a diagnosis or ruling out of cancer within 28 days of being referred urgently by their GP for suspected cancer.

Initial tests

Initial tests to diagnose ovarian cancer may include:

• An examination by a doctor. He or she may feel an enlarged ovary or another suspicious abnormality.

• An ultrasound scan. This is a painless test which uses sound waves to create images of structures inside your body. The probe of the scanner may be placed on your lower tummy (abdomen) to scan the ovaries. A small probe is also commonly placed inside the vagina to scan the ovaries from this angle in order to obtain more detailed pictures.

• A blood test. A sample of blood can detect a protein called CA 125. The level of CA 125 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 (benign) conditions can also cause a high level. This means that this test does not conclusively diagnose or rule out ovarian cancer but it can be a helpful test. This test is also often used to monitor the effects of treatment for ovarian cancer.

Further tests

You may be advised to have further tests, depending on the symptoms that 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 cancer has grown and whether it has grown into other nearby structures, such as the womb (uterus), bladder or back passage (rectum).

• Whether the cancer has spread to local lymph glands (nodes).

• Whether the cancer has spread to other areas of the body (metastasised).

Tests that are used may include one or more of the following:

• Computerised tomography (CT) scan of the lower abdomen. This can provide detail of the structure of the internal organs.

• A chest X-ray 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. If you are aged under 40 years you may have other tests to check for the rarer types of ovarian cancer.

• Removal (aspiration) of fluid. If your abdomen has swollen with fluid leading to a collection of fluid in the abdomen (ascites) then a sample can be taken. This is done by numbing a small area of skin on the abdomen, using local anaesthetic. A fine needle is then inserted through the abdominal wall and some fluid is drawn out. This fluid can then be looked at under the microscope to look for cancer cells.

• Even if you do not have fluid in the abdomen, cells may still be obtained by passing a needle through the skin into the abdomen. This is done accurately with the help of an ultrasound or CT scan (percutaneous image-guided biopsy).

• 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 cut (incision) in the skin. The ovaries and other internal organs can be seen. You would normally have a general anaesthetic for this. Also, small samples (biopsies) can be taken to be looked at under the microscope to detect and confirm cancer cells.

Ovarian cancer treatment

Treatment options may include surgery, chemotherapy and occasionally radiotherapy. The treatment advised in each case depends on various factors such as the stage, type and subtype of the cancer and your general health.

A specialist will be able to give the pros and cons, likely success rate, possible side-effects and other details about the various possible treatment options for your type and stage of cancer.

You should also discuss with your specialist the aims of treatment. For example:

• In some cases, treatment aims to cure the cancer. (Doctors tend to use the word remission rather than the word cured. Remission means there is no sign of cancer following treatment. If you are in remission, you may be cured. However, in some cases a cancer returns months or years later. This is why doctors are sometimes reluctant to use the word cured.)

• In some cases, treatment aims to control the cancer. If a cure is not realistic, with treatment it is often possible to limit the growth or spread of the cancer so that it progresses less rapidly. This may keep you free of symptoms for some time.

• In some cases, treatment aims to ease symptoms. For example, if a cancer is advanced then you may require treatments such as painkillers or other treatments to help keep you free of pain or other symptoms. Some treatments may be used to reduce the size of a cancer, which may ease symptoms such as pain.

Surgery

An operation is advised in most cases. If the cancer is at a very early stage (just confined to the ovary and not spread) then an operation to remove the affected ovary and associated Fallopian tube may be all the treatment required.

However, in many cases the cancer has grown into other nearby structures or has spread. Therefore, a more extensive operation is often needed. For example, the operation may involve removing the affected ovary, plus the womb (uterus), the other ovary and also other affected areas in the lower tummy (abdomen).

During the operation the surgeon may take small samples (biopsies) from structures in the abdomen and from structures lining the abdomen, such as the diaphragm or lymph glands (nodes).

The samples are looked at under the microscope to see if any cancer cells have spread to these structures. This helps to give an accurate staging and helps to decide on further treatment.

Chemotherapy

Chemotherapy is a treatment of cancer by using anti-cancer drugs which kill cancer cells or stop them from multiplying.

In some cases, cells taken during surgery or at biopsy will be looked at under a microscope to check the risk of the cancer returning. If the risk is high, you will be offered chemotherapy. In other cases chemotherapy is given before surgery to make it more successful.

Newer treatment options for relapsed ovarian cancer

NICE has approved medicines called niraparib and olaparib for some women with ovarian cancer. These treatments are for women with ovarian, Fallopian tube and peritoneal cancer which is sensitive to platinum-based treatments but whose cancer has returned.

In these women, Niraparib and olaparib have been found to increase the time before the cancer progresses. They may also extend how long they live. If you have had at least two courses of platinum-based chemotherapy and your disease has come back, your doctor may recommend one of these treatments as an option.

Radiotherapy

Radiotherapy is a treatment that uses high-energy beams of radiation which are focused on cancerous (malignant) tissue. This kills cancer cells or stops cancer cells from multiplying.

Radiotherapy is not often used for ovarian cancer. It is sometimes used following surgery, to kill cancer cells which may have been left behind after the operation. Radiotherapy may also be used to shrink secondary tumours that have developed in other parts of the body and are causing pain or other symptoms.

Ovarian cancer prognosis

There is a good chance of a cure if ovarian cancer is diagnosed and treated when the disease is at an early stage (confined to the ovary and has not spread).

Unfortunately, most epithelial ovarian cancers are not diagnosed at an early stage. This is because symptoms often do not occur until after the cancer has grown quite large or has spread. In this situation, a cure is less likely but still possible.

In general, the later the stage and the higher the grade of the cancer, the poorer the outlook (prognosis). Even if a cure is not possible, treatment can often slow down the progression of the cancer.

Chemotherapy is very effective for cancer of the ovary and works well in most cases. However, the cancer can come back and does so in about three quarters of cases. Chemotherapy then does not work so well the second time. New treatments are being developed which show promise for treating cancer which comes back.

Overall at the current time, around 46 women in 100 diagnosed with ovarian cancer (of all types and stages) will be alive five years later. However, the outcome depends on the type of cancer and on the stage at which it is diagnosed.

The treatment of cancer is a developing area of medicine. New treatments continue to be developed and the information about outlook given above is very general. The specialist who knows your case can give more accurate information about your particular outlook and how well your cancer is likely to respond to treatment.

Is there a screening test for ovarian cancer?

Currently there is no ovarian cancer screening test that is offered to all susceptible people in the UK. Types of screening tests currently available are the CA 125 blood test and regular ultrasound scan of the ovary.

The UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) was designed to look at the effect of screening - the pros and cons. The results were reported in 2023.

In this study 202,638 post-menopausal average risk women were included: 50,640 women were randomised to multimodal screening (blood tests and ultrasound), 50,639 had ultrasound based screening and 101,359 were in the control group.

Many ovarian cancers were detected in women with no symptoms at an early stage. Unfortunately, this did not always mean there was a lower risk of death. Additionally, many women who had an abnormal screening test had unnecessary surgery, as they were found not to have ovarian cancer.

Their conclusion was that screening using the CA125 blood test or ultrasound scan to test for ovarian cancer did not save lives. Additionally, it was associated with some harm. Therefore, an ovarian cancer screening programme for most women cannot be currently recommended.

Some people are currently offered screening if they have a strong family history of ovarian cancer. If you have two or more close relatives (sister, mother, aunt) who have had ovarian cancer or you have members in the family who have had breast cancer at a young age then you should talk with your doctor to see if you would benefit from screening.