Conditions > Trophoblastic diseases

Trophoblastic diseases

Clinical picture

Trophoblastic diseases are rare cancerous conditions that develop in the trophoblast. Trophoblastic cells form the placenta during pregnancy.

There are several types of trophoblastic disease:

Mola pregnancy (mola hydatidosa, gestational trophoblastic disease):

- a complete mola pregnancy;
- a partial mola pregnancy;
Post-mola gestational trophoblastic neoplasia:
- a choriocarcinoma;
- placental site trophoblastic tumour (PSTT);
- epithelioid trophoblastic tumour.

Choriocarcinomas, placental site trophoblastic tumours and epithelioid trophoblastic tumours are considered as cancers.

In a complete mola pregnancy, there is too much DNA from the father and none from the mother. A partial mola pregnancy shows some DNA from the mother but an excess of DNA from the father. As a result, there are too many chromosomes. Gestation may occur, but the foetus will normally not be able to live.

During pregnancy, trophoblastic cells produce the hormone hCG, human chorionic gonadotrophin. If, after a mola pregnancy production does not return to normal levels, it is known as a condition called post-mola gestational trophoblastic neoplasia or persisting trophoblast. This occurs in around 15% of all mola pregnancies.

There are three types of persisting trophoblast: choriocarcinoma, PSTT and epithelioid trophoblastic tumour. A choriocarcinoma is a tumour consisting of trophoblastic cells where hCG has not returned to normal levels. This causes damage to the muscles and blood vessels of the uterus. This type of cancer can spread to the lungs, the liver and the brain. Choriocarcinomas can also occur after a miscarriage.

PSTT are rare tumours that develop in the location where the placenta attaches to the uterus. Cancerous cells grow into the muscle of the uterus and adjacent blood vessels. PSTT tumours produce little hCG, and the same goes for epithelioid trophoblastic tumours. These are relatively slow growing and bear a resemblance to squamous cell carcinoma. These tumours can occur years after a pregnancy. Around 30% of them spread to other organs.

Symptoms

Women with excess concentrations of the hCG hormone can present the following symptoms:

pregnancy-related complaints such as nausea and vomiting
overactive thyroids
pre-eclampsia
anaemia

Cause

No direct cause for trophoblastic diseases is known. There are also no known, clearly identified risk factors.

Diagnosis

A GP that suspects a patient has a trophoblastic disease will refer her to a gynaecologist. The gynaecologist will perform an ultrasound and will do a physical examination. In this setting, an internal examination of the vagina and cervix is also indicated. An internal ultrasound (also known as a transvaginal ultrasound) will provide information regarding the ovaries and the uterus.

After diagnosis, subsequent tests may be done in order to establish how far the disease has developed. These tests include lung X-rays, CT scans and MRI scans.

Trophoblastic diseases are graded along four stages:

Stage I: The tumours are contained within the uterus
Stage II: The tumours have spread beyond the uterus but only affect the reproductive organs
Stage III: The tumours have spread to the lungs
Stage IV: The tumours have spread to other parts of the body

Treatment

Trophoblastic diseases can be treated in the following manners:

Curettage:
- Mola pregnancies (both complete and partial) are treated by means of a vacuum curettage, during which the contents of the uterus are sucked out. This method can result in significant blood loss; more than a miscarriage.
hCG-monitoring:
- After a mola pregnancy, hCG concentrations have to be monitored weekly until normal values have returned. After that, a check every six months will suffice.
Hysterectomy:
- If a patient is over 40 years old and no longer desires to become pregnant, a doctor can decide to remove the entire womb. This method is also used in women with PSTT tumours, since these are not susceptible to radiation therapy.
Chemotherapy
- Chemotherapy is mostly used in patients with persistent trophoblast disease. In a low-risk scenario this will usually entail one type of chemotherapy; but in a high-risk situation, several types of chemo are combined. This happens when the tumours have spread to the liver or the brains, when a tumour develops before a full-term pregnancy, when normal chemotherapy has no effect or when treatment starts one year after curettage.