**2. Histological classification**

Endometrial cancer can be divided into two histologic subtypes: Type I and Type II. Type I endometrial cancers account for the majority of uterine cancer cases and occur more commonly in association with overexposure to estrogen. They are of endometrioid histology, diagnosed in early stages, and are commonly associated with K-ras, PTEN, and/or mismatch repair gene mutations. They are also associated with obesity. Type II endometrial cancers, on the other hand, are typically of aggressive non endometrioid histology and are therefore more commonly diagnosed in advanced stages. They often develop in a background of atrophic endometrium (Bokhman 1983) and have a greater probability of having p53 mutations and/or HER2/neu over expression (Prat et al. 2007).
