Short tandem repeat analysis to identify the causative pregnancy of high-risk gestational trophoblastic neoplasia: Molar versus nonmolar pregnancy and its relation to the outcome

Abstract

IntroductionGestational trophoblastic neoplasia (GTN) include a group of malignant neoplasms that originate from the trophoblasts of placental tissue in molar or nonmolar pregnancy. Currently, it is unclear whether the prognosis of high-risk GTN or gestational choriocarcinoma succeeding molar pregnancy or that following a nonmolar one is better. Comparison of the genetic short tandem repeat (STR) patterns of the DNA extracted from the tumor, patient, and her partner allows the genetic origins of the choriocarcinoma to be distinguished - whether it is gestational or non-gestational and whether it is derived from a molar or nonmolar pregnancy in the event it is gestational. This study aimed to investigate the causative pregnancy of patients with high-risk GTN, especially those with poor outcomes, and assess the impact of the causative pregnancy on patient outcome. MethodsWe evaluated 24 patients who were diagnosed with high-risk GTN between January 2000 and October 2019, including 15 cases of pathologically proven gestational choriocarcinomas and the causative pregnancy was investigated by STR analysis in which tumor DNA could be extracted. ResultsIn high-risk GTN without history of anteceding molar pregnancies, nonmolar pregnancy was the causative pregnancy, which was confirmed in three cases. Molar pregnancy appeared be the causative pregnancy of high-risk GTN in patients with a history of antecedent molar pregnancies either with or without interruption by subsequent nonmolar pregnancies prior to developing high-risk GTN. High-risk GTN in most of the evaluated deceased cases (three of four) was due to nonmolar pregnancy, while all but one case with molar pregnancy as the causative pregnancy survived. DiscussionSTR analysis can distinguish the causative pregnancy of high-risk GTN, and nonmolar pregnancy as the causative pregnancy might have negative effects on the outcome of the disease.