Dualistic model of molecular pathogenesis in endometrial carcinoma

Abstract

Sporadic endometrial carcinoma can be divided into two biologically and clinically distinctive subtypes of which one is estrogen-related (type I), the other estrogen-unrelated (type II). Type I carcinomas occur at younger age, express estrogen (ER) and progesterone receptors (PR), are frequently associated with endometrial hyperplasia and show a good prognosis. Type II carcinomas occur at older age, are negative for ER and PR, arise in the background of atrophic endometrium and show poor prognosis. Histologically, endometrioid carcinomas correspond to type I carcinomas whereas serous carcinoma is the prototype of type II carcinomas. Endometrioid and serous carcinomas are significantly different with respect to their molecular changes. Endometrioid carcinomas frequently show microsatellite instability (MIN), PTEN and K-ras mutation but infrequently p53 mutations, loss of p16 expression and her2/neu amplification, respectively. In contrast, serous carcinomas show a high frequency of p53 mutations and often loss of p16 expression whereas MIN and PTEN and K-ras mutations are uncommon. Familial endometrial carcinoma associated with HNPCC occur about two decades earlier than sporadic carcinomas, show endometrioid histology and are frequently MIN positiv due to germline mutations of mismatch repair genes (mostly MLH1 and MSH2). During the progression of endometrioid carcinoma PTEN mutations and MIN are considered early changes since they are present in a high frequency in atypical endometrial hyperplasia whereas p53 mutations, loss of p16 expression and her2/neu amplification are considered late events since they are predominantly found in poorly differentiated tumors. In contrast, p53 mutations are considered an early event in the pathogenesis of serous carcinoma occurring already in its putative precursor endometrial intraepithelial carcinoma (EIC). The future research will focus, besides the discovery of new relevant genes, on the interaction of known genes as well as their clinical relevance.