Endometrial cancer is the fifth most common cancer diagnosed in women in developed countries. This research used genetics to assess relationships between endometrial cancer and, previously identified and novel, risk factors. This work brings new insights by providing evidence that HDL and LDL cholesterol levels are linked to endometrial cancer risk. Further, I have shown that two gynaecological diseases, which are comorbid with endometrial cancer, also share genetic risk architecture with endometrial cancer. This work also advances the understanding of biological mechanisms of endometrial cancer by identifying candidate susceptibility genes.