Gestational Trophoblastic Disease Stages

After a woman is diagnosed with gestational trophoblastic disease (GTD), doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.

GTD stages range from stage I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

How is the stage determined?

The 2 systems used for staging GTD, the FIGO (International Federation of Gynecology and Obstetrics) system and the AJCC (American Joint Committee on Cancer) TNM staging system are basically the same.

They both use 2 factors to stage (classify) this cancer:

  • The extent (size) of the tumor (T): How far has the cancer grown into the uterus? Has the cancer reached nearby structures or organs?
  • The spread (metastasis) to distant sites (M): Has the cancer spread to the lungs or other distant organs?

Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage. In the case of GTD, the spread to nearby lymph nodes (N) is not used because the cancer rarely spreads there. If the cancer does spread to the lymph nodes it is categorized as M1b (metastasis).

The staging system in the table below uses the clinical stage. It is based on the results of physical exam, biopsy, and imaging tests done before surgery. If surgery is done, a pathologic stage can be determined from the findings at surgery, but it does not change your clinical stage. Your treatment plan is based on the clinical stage. For more information see Cancer Staging.

The system described below is the most recent AJCC system, effective January 2018. It is the staging system for invasive moles, choriocarcinoma, placental site trophoblastic tumor, and epithelioid trophoblastic tumor.

Risk score

Stage is also used to predict a patient’s outlook. Because treatment for GTD is usually effective regardless of the extent of the disease, other factors such as a woman's age, length of time since pregnancy, and HCG level are more useful in predicting a woman's outlook (prognosis). These factors are taken into account in a scoring system.

Prognostic scoring system

In the United States, most cancer centers use a system that describes women with persistent GTD according to their outlook, based on several factors.

Age

Score

Younger than 40

0

40 or older

1

   

Preceding pregnancy

Score

Molar pregnancy

0

Abortion (includes miscarriage)

1

Birth (term pregnancy)

2

   

Time since pregnancy

Score

Less than 4 months

0

At least 4 months but less than 7 months

1

7 to 12 months

2

More than 12 months

4

   

Blood HCG level (IU/L) pre-treatment

Score

Less than 1,000

0

1,000 − 9,999

1

10,000 − 99,999

2

100,000 or more

4

   

Largest tumor size,

including the original one

in the uterus

Score

Less than 3 cm (1.2 inches) across

0

At least 3 cm but less than 5 cm (2 inches)

1

5 cm or more

2

   

Site of metastases (if any)

Score

Lung

0

Spleen, kidney

1

Gastrointestinal tract

2

Brain, liver

4

   

Number of metastases found

Score

0

0

1 to 4

1

5 to 8

2

More than 8

4

   

Failed chemotherapy

Score

None

0

Single drug

2

2 or more drugs

4

The numbers are then added up, and the overall score determines a woman's risk level.

  • Women with a score of 6 or less are at low risk and tend to have a good outlook regardless of how far the cancer has spread. The tumor(s) will usually respond well to chemotherapy.
  • Women with a score of 7 or more are at high risk, and their tumors tend to respond less well to chemotherapy, even if they haven't spread much. They may require more intensive chemotherapy.

The final stage is the anatomic stage with the actual prognostic score number shown together (separated by a colon). An example of this is II:5.

GTD staging can be complex, so ask your doctor to explain it to you in a way you understand.  

 

AJCC Stage

Stage grouping

FIGO Stage

Stage description*

I: risk score

T1

M0

I

The cancer is within the uterus. (T1).

It has not spread to the lungs or other distant sites (M0).

II: risk score

T2

M0

II

The cancer has grown outside the uterus into other genital structures (like the vagina or ovaries) (T2).

It has not spread outside the pelvis to the lungs or to other distant sites (M0).

III: risk score

 

Any T

M1a

III

The tumor has spread to the lungs (M1a).

It might also involve genital structures such as the vagina or vulva (Any T).

IV: risk score

Any T

M1b

IV

 

The cancer has spread to distant organs such as the brain, liver, kidneys, spleen and/or gastrointestinal (GI) tract (M1b).

It might also involve genital structures such as the vagina or vulva (Any T).

 

 

* The T categories are described in the table above, except for: TX: Main tumor cannot be assessed due to lack of information. T0: No evidence of a primary tumor. 

 

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: December 20, 2017 Last Revised: December 20, 2017

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