Definition and Types of Gestational Trophoblastic Diseases

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Gestational Trophoblastic Diseases and Gestational Trophoblastic Neoplasia (GTN)

Gestational trophoblastic disease is an ABNORMAL PREGNANCY FORM CREATED BY AN ABNORMALLY GROWING PLACENTA that develops due to plantation of fertilized ovum which is non-viable into the uterus and its pathological growth

The Word “gestation” means pregnancy and “trophoblast” is the name of cells that form the placenta. “Trophoblast” cells form the placenta and the disease develops subsequent to pregnancy as a result of abnormal development of these cells. In GTD group, there are subtypes benign and malign and the malign form may metastasize. Some researchers believe that mole hydatidiform and its subtypes must be understood of GTD and it must be named gestational trophoblastic neoplasia (GTN) when a malign form develops. I also defend this theory. Therefore, especially for metastatic GTD, I will use the term GTN. Although these are academic debates, I think it is important for you patients because you hear so many names when you read different sources, so I know that you ask what this is all about 🙂

GTDs are separated into 4 main groups histopathologicly:

1. Mole hydatidiform: a. complete mole b. partial mole

2. Invasive mole

3. Choriocarcinoma

4. Tumors that derive from the placental site

 

Prognostic factors and staging of GTD:

It has always been argued whether the histopathologic subtypes of GTD, namely its cellular subtypes, are efficient on the prognosis or not. However, it has been considered that histopathology is insufficient in the definition of prognosis. Thus, many staging and scoring methods have been developed by various establishments.

There are staging and scoring systems prepared by WHO, NIH and FIGO.

There are 9 factors in scoring of WHO classification. Although 9 risk factors have been considered to be too many and complicated, classification is easy and histopathology dominant. FIGO (international association of gynecologists) used anatomic localization of the disease in the classification. Today, a mixture of these two classifications is being used.

Staging:

Stage I: Disease is in the uterus

Stage II: Disease is outside the uterus but limited to genital organs

Stage III: Lung metastasis whether or not genital system affection is present

Stage IV: Distant metastasis

Modified WHO GTD Scoring System

 RISK FACTORS

0

1

2

4

Age

<40

≥40

Prior pregnancy

Mole

Misscarriage

Term pregnancy

Duration between prior and molar pregnancy

<4

4–6

7–12

>12

Serum hCG (IU/L) levels before treatment

<103

103–104

104–105

>105

Size of the largest tumor including the uterus

<3

3–4 cm

≥5 cm

Metastasis sites

Lung

Spleen,
Kidney

Intestinal
system

Liver,
Brain

Metastasis amount

1–4

5–8

>8

Prior unsuccessful chemotherapy amount

Single drug

≥2 drugs

Women who have a score of 7 and above are considered to be HIGH RISKY.