But other studies had showed no association when corrected for age. Pathogenesis
At the cellular level, any abnormalities in the placental trophoblastic proliferation could potentially contribute to molar pregnancy and tumor development. There are three different types of trophoblasts: cytotrophoblasts, syncytiotrophoblasts, and intermediate trophoblasts. Each of them possesses distinct specialized functions to support a developing embryo. Cytotrophoblasts are the germinating cells that forms the chorion villi and can be differentiated into syncytiotrophoblasts which produce hCG and can intrude to the inner muscle layer of the uterus to help embed the developing embryo, and intermediate trophoblasts which spread throughout the chorion villi to support maternal-fetal circulation. Malignant cellular transformation of all of these three trophoblastic cells contribute to the development of gestational choriocarcinoma. Common pathological features of GC include abnormal trophoblastic enlargement, loss of trophoblastic specialized features and functions, absence of villi in the placenta, abnormal bleeding, and necrosis.Many efforts have been made to try to understand the mechanism of how non-malignant mole could become invasive. It is suspected that activation of certain oncogenes (such as up-regulations of MDM2, c-ERB2, and BLC2) and inactivation of tumor suppressor genes (such as up-regulations of p53, p21) were involved in the processes of genetic changes in this malignant transformation. But trophoblastic cells, by nature, are highly active in cell division, the increased activities of those genes are also necessary to maintain their normal cell function. Therefore, it is still unclear how significantly these genetic changes are in the pathogenesis of gestational choriocarcinoma.
Recent research in the role of long non-coding RNAs (lncRNAs) in the GC development is believed to bring hope in this field. Long non-coding RNAs are groups of RNAs that do not code for protein expression and are usually over 200 nucleotides long; they are increasingly recognized to have essential role in many aspects of cellular function, like transcriptional regulation, sub-cellular protein localization, and epigenetic remodeling. To date, several types of lncRNAs are reported to have role in GC pathogenesis, which are metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), H19, maternally expressed gene 3 (MEG3), prostate cancer antigen 3 (PCA3), the long intergenic non-coding RNA 00261 (LINC00261), etc.. However, as many of these studies are still in the preliminary stages, more investigation is needed to fully understand the underlying mechanism. Diagnosis
Common characteristic manifestations of gestational choriocarcinoma include irregular vaginal bleeding and hydatidiform moles. A hydatidiform mole is a red hemorrhagic mass with various sizes in the uterus. Often, diagnosis is presumptive. It is based on clinical findings and the identification of a malignant trophoblast. One prevalent symptom is vaginal bleeding after a pregnancy, abortion, or hydatidiform mole. In the presence of choriocarcinoma, a pregnancy test will be positive even if there is no embryo/fetus.A confirmed diagnosis usually happens after the disease has progressed to a late clinical stage. This is partly due to the wide spectrum and rare clinical presentations of the disease.