MALIGNANT GESTATIONAL TROPHOBLASTIC NEOPLASIA
Postmolar or persistent GTD is only one of the many forms of malignant GTD. Although invasive moles are his-tologically identical to antecedent molar pregnancies while invading the myometrium, choriocarcinomas are a malig-nant transformation of trophoblastic tissue. Instead of hydropic chorionic villi, the tumor has a red granular appearance on cut suction and consists of intermingled syncytiotrophoblastic and cytotrophoblastic elements with many abnormal cellular forms. Clinically, choriocarcino-mas are characterized by rapid myometrial and uterine-vessel invasion and systemic metastases resulting from hematogenous embolization. Lung, vagina, central ner-vous system, kidney, and liver are common metastatic loca-tions. Choriocarcinoma may follow a molar pregnancy, normal-term pregnancy, abortion, or ectopic pregnancy. In the United States, choriocarcinoma is associated with approximately 1 in 150,000 pregnancies, 1 in 15,000 abor-tions, 1 in 5000 ectopic pregnancies, and 1 in 40 molar pregnancies.
Early identification and treatment are important. Abnormal bleeding for more than 6 weeks after any pregnancy should be evaluated with hCG testing to exclude a new pregnancy or GTD. Failure of quantitative hCG levels to regress aftertreatment of a molar pregnancy suggests that further treat-ment is needed. Identified metastatic sites should not be biopsied to avoid bleeding complications. Most GTN,including malignant forms, are highly sensitive to chemotherapy and often results in a cure, allowing for future reproduction.
Nonmetastatic persistent GTN is completely treated by single-agent chemotherapy. Single-agent chemotherapy iseither methotrexate or actinomycin D. The prognosis for metastatic GTN is more complex, divided into good and poor prognostic categories (Table 41-2). The World Health Organization (WHO) has developed a prognostic scoring system for GTN that includes a number of epi-demiologic and laboratory findings; this system was later combined into the International Federation of Gynecology and Obstetrics (FIGO) staging system (Table 41-3). A FIGOscore of 7 or above classifies metastatic GTN as high-risk, requir-ing multi-agent chemotherapy. The combination chemother-apeutic regimen with the highest success rates is: etoposide,methotrexate, actinomycin D, cyclophosphamide, andOncovin (vincristine)) [EMACO]. Adjunctive radiother-apy is sometimes performed with patients who have brain or liver metastasis. Surgery may be necessary to control hem-orrhage, remove chemotherapy-resistant disease, and treat other complications to stabilize high-risk patients during intensive chemotherapy. Cure rates for non-metastatic and good-prognosis metastatic disease approach 100%. Cute rates for poor-prognosis metastatic disease are 80% to 90%.