The identification of two subgroups of obese women with differing endometrial proliferation levels: potential consequences in the development of endometrial cancer.

Enhanced endometrial proliferation correlates obesity to type-I (estrogen-dependent) endometrial cancer (EC). Our aim was to distinguish obese women (without EC) with differing endometrial proliferation. Endometrial and blood samples were obtained from normal-weight and obese women without EC. Type-I EC samples were obtained from obese patients. On measuring endometrial proliferation (Ki67 and phosphorylated histone H3 (p-H3)), two groups of obese women without EC were identified: obese(High Proliferating) (O(HP)) and obese(Low Proliferating) (O(LP)). Increased Ki67 (88.5%, P<0.001), p-H3 (62.6%, P<0.01), 17β-estradiol/progesterone ratio (46.3%, P<0.01) and endometrial estrogen receptor alpha (ERα) (82.2%, P<0.001) were observed in O(HP) compared with O(LP) patients. ECs possessed similar ERα and enhanced proliferation as O(HP), suggesting that O(HP) women are at higher risk of type-I EC. O(LP) women were indistinguishable from normal-weight women regarding these determinants of endometrial proliferation, ERα and 17β-estradiol/progesterone ratio. Our data may further define the obesity phenotype in regards to type-I EC risk and may help identify obese women more susceptible to develop type-I EC, allowing early intervention and a potential reduction in mortality.