(26) Choriocarcinoma

CHORIOCARCINOMA

 Choriocarcinoma

is a rarely occurring, highly malignant tumour that arises from the trophoblastic epithelium.  It is characterized by producing enormous amounts of β-hCG, by its early blood borne metastases to the lungs, liver and brain, and by being extremely sensitive to chemotherapeutic agents.

Classification of Gestational Trophoblastic Disease (GTD): Benign

Malignant

Hydatidiform Mole

Choriocarcinoma

A) Complete Mole

A) Non metastatic

B) Partial Mole

B) Metastatic - Low risk - High risk

INCIDENCE:  It

occurs in about 1/50000 pregnancies, and is nearly 10 times higher in the far-east countries than in other regions in the world.  About 50% of choriocarcinomas follow a molar pregnancy, 30% occur after abortion and 20% follow a normal pregnancy. It may rarely occur after ectopic pregnancies.

Low-risk and high-risk cases are classified according to several factors

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Age of patient and type of antecedent pregnancy (mole, abortion or term pregnancy). Duration between antecedent pregnancy and diagnosis of choriocarcinoma. Level of serum β-hCG, and tumour size. Site and number of metastatic lesions, and previous response to chemotherapy treatment.

GROSS PATHOLOGY  Multiple

haemorrhagic nodules of variable size invading the myometrium.  Central necrosis, surrounded by a rim of viable tumour disrupting the muscle fibres and invading maternal vessels.  Genital and extragenital haematogenous spread occurs in about 50% of cases.

MICROSCOPIC PATHOLOGY  Central

core of mononuclear cytotrophoblast surrounded by a rim of multinucleated syncytiotrophoblast.  Distinct characteristic absence of chorionic villi.  Extensive areas of necrosis and haemorrhage.

SPREAD OF CHORIOCARCINOMA  A)

Haematogenous spread: choriocarcinoma is famous for its early and widespread blood borne metastases to various sites including;  Pulmonary metastases (up to 80% of cases)  Vaginal metastases (30%)  Hepatic metastases (10%)  CNS, especially brain metastases (10%)

 B)

Direct spread: Direct myometrial invasion is not uncommon.

CLINICAL PRESENTATION 

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Persistent abnormal symptoms and signs after pregnancy termination, molar evacuation, abortion Symptoms and signs include; Persistent vaginal bleeding, enlarged or subinvoluted uterus, persistent theca lutein cysts of the ovaries. Pain after molar evacuation, is a rare presentation.

DIAGNOSIS OF CHORIOCARCINOMA  

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Abnormally elevated serum β-hCG levels on diagnosis of a molar pregnancy. Abnormal postmolar- regression curve (PMRC) i.e. persistent, high β-hCG levels after molar evacuation, or pregnancy termination, with failure to decline gradually in the first few weeks. Empty uterus by ultrasonography (no residual molar contents). Dilatation and curettage (D&C) operation may help in diagnosing those cases in which the tumour is still present within the endometrial cavity or cases with myometrial invasion.

Metastatic work-up includes 

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Pelvic TVS & TAS, to evaluate uterus (residual contents) and adnexae (theca lutein cysts). Chest X ray, to detect lung metastases. Abdominal US, to detect liver metastases. C.T. scan, to diagnose liver, lung and brain metastases. MRI may detect myometrial invasion (Invasive mole).

TREATMENT OF CHORIOCARCINOMA 

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Chemotherapy is the preferred and most effective line of treatment in the vast majority of the cases as the tumour is generally chemosensitive. Chemotherapy also has the benefit of treating distant metastases effectively. Single agent chemotherapy: (methotrexate) for non-metastatic and low- risk cases. Combination chemotherapy is indicated in metastatic high- risk cases.

 Surgery:

in the form of TAH-BSO has a limited role in choriocarcinoma. It may be indicated in the multiparous elderly patient, with other possible complications as severe intractable bleeding, pyometra, perforation, or associated uterine or ovarian pathology

 Complete

remission: Defined as an hCG titre that remains negative for three consecutive weeks even in the presence of non-viable metastases.  Cure is considered if the patient is diseasefree for five years.