Cancer originating from this lining is the most common malignancy of the uterus and also the most common malignancy of the reproductive organs. Endometrial cancer occurs most often between the ages of 55 and 75. Women who develop this cancer before age 45 usually have a preceding history of infrequent or absent menstrual periods. Abnormal uterine bleeding has many causes. Two of the most important causes are bleeding due to endometrial cancer and bleeding due to endometrial hyperlasia.
Hyperplasia means excessive growth, and some forms of hyperplasia are precancerous.
Hyperplasia of the endometrium can occur from stimulation by too much estrogen or from prolonged estrogen exposure. Estrogen is a hormone naturally present in the body and primarily controlled by the ovaries. It is also a major component of contraceptive pills and of the medications used after menopause for homone replacement therapy. The estrogen is not by itself the problem, but the wrong amount and constant exposure can cause hyperplasia. The endometrial lining is lost from the body and a new lining develops with each menstrual cycle.