Staging of invasive mole and choriocarcinoma

The stage of an invasive mole or choriocarcinoma means the extent of the cancer. For example, whether it is just in the womb, outside of the womb or has spread to other areas of the body.

Staging is important because it helps your doctors decide what treatment you need. You will have tests and scans to find the stage.

The FIGO/WHO staging system

An invasive mole is a cancer that can form in the womb after an abnormal type of pregnancy called a molar pregnancy. It is also called persistent trophoblastic disease (PTD). Choriocarcinoma is a very rare cancer that can occur after a normal pregnancy, a molar pregnancy, a miscarriage or a termination of pregnancy (abortion).

The staging system used for invasive mole and choriocarcinoma is called the FIGO/WHO staging system. This looks at the stage of disease and a risk factor score. These are used together to work out which treatment you need.

A numbering system is used for both the stage and risk factor score.

After removal of a molar pregnancy you have regular blood and urine tests to check the levels of a hormone called human chorionic gonadotrophin (hCG).

If the levels of hCG don't go down this is a sign that abnormal cells are present in the body. You will have tests to find out where the cells are and whether they have spread. 

Your doctor will also do tests if:

  • there is evidence of choriocarcinoma in the tissue sample taken during removal of a molar pregnancy
  • you have heavy vaginal bleeding and, or severe abdominal pain

The number stages of invasive mole and choriocarcinoma

There are 4 main stages. Stage 1 is an early tumour and stage 4 the most advanced.

Stage 1

This is the earliest stage when the cancer is only in the womb (uterus).

Diagram showing stage 1 choriocarcinoma

Stage 2

This is when the disease has spread outside the womb to genital areas nearby, such as the vagina or ovary. It has not spread outside the pelvis.

Diagram showing stage 2 choriocarcinoma

Stage 3

The cancer has spread to the lungs and may or may not be in the local area around the womb.

Diagram showing stage 3 choriocarcinoma

Stage 4

The cancer has spread (metastasised) to other parts of the body, such as the liver or brain. 

Diagram showing stage 4 choriocarcinoma

About risk factors

When you are diagnosed with an invasive mole or choriocarcinoma your doctors look at certain risk factors. 

The scores for each risk factor are 0,1, 2 and 4. The risk factors are:

  • age – the younger you are, the lower your score
  • the type of pregnancy you had – a molar pregnancy is low risk, an abortion or miscarriage means a middle score, and full term pregnancy gives a higher score
  • time between the pregnancy and your diagnosis – less than 4 months is a low score and more than a year is a higher score
  • the hCG level in the blood – the higher the level of hCG the greater the score
  • the amount of disease spread – the more areas of your body the disease has spread to, the higher the score
  • the parts of your body affected – cancer spread to the lungs or vagina is a low score, to the spleen or kidneys is a slightly higher score, and spread to the brain or liver is higher again
  • the size of the cancer – the larger the cancer, the greater the score
  • previous chemotherapy – if you have already had chemotherapy for your GTD but it has come back, this increases your score

The doctors add up your scores to give a total and they group women into 3 groups:

  • low risk – a score of 6 or less
  • high risk – a score of 7 to 12
  • ultra high risk – a score of 13 or above

Your risk score helps your doctors decide which chemotherapy treatment is best for you.

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