Placental site trophoblastic tumor: A study of 55 cases and review of the literature emphasizing factors of prognostic significance.
Academic Article
Overview
abstract
OBJECTIVE: The placental site trophoblastic tumor is a rare form of gestational trophoblastic disease. Fifteen percent of reported cases have been fatal, but predicting behavior in individual patients has been challenging. METHODS: The clinical, gross and histopathological features of 55 cases and 180 cases in the literature were analyzed for their effect on survival and in relation to tumor stage. RESULTS: The 55 patients in our series were 20 to 62 (average 32) years of age. The tumors occurred on an average of 34 months after the last known gestation. 84% were stage I, 2% stage II, 5% stage III, and 9% stage IV. Serum levels of human chorionic gonadotropin (hCG) were elevated (average 691 mIU/ml) in 77% of the cases. The tumors were on average 5 cm in greatest dimension and were composed microscopically of infiltrative sheets of intermediate (extravillous) trophoblastic cells. The mitotic rate ranged from 0 to 20 (average 5.0) per 10 high power fields. The follow-up interval averaged 4.6 years. Eight patients (15%) died from metastatic tumor, and nine additional patients had metastases or a recurrence but were alive at last contact. The most common metastatic sites were the lungs, liver, and vagina. CONCLUSIONS: Significant factors associated with adverse survival in the present series were age over 35 years (P = 0.025), interval since the last pregnancy of over 2 years (P = 0.014), deep myometrial invasion (P = 0.006), stage III or IV (P < 0.0005), maximum hCG level > 1000 mIU/ml (P = 0.034), extensive coagulative necrosis (P = 0.024), high mitotic rate (P = 0.005), and the presence of cells with clear cytoplasm (P < 0.0005). Only stage and clear cytoplasm were independent predictors of overall survival, while stage and age were the only independent predictors of time to recurrence or disease-free survival. In the literature, factors associated with survival were stage (P < 0.005), interval from preceding pregnancy of over 2 years (P = 0.029), previous term pregnancy (P = 0.046), high mitotic rate (P < 0.0005), and high hCG level (P = 0.037).
