Endometrial thickening is not necessarily cancerous. Causes of endometrial thickening generally include irregular hyperplasia or endometrial polyps, both of which can lead to thickening of the endometrium, but this is not necessarily indicative of cancer. Whether it is endometrial cancer is usually determined if patients with endometrial thickening do not show clear improvement after treatment with medication. Typically, a curettage procedure is performed to collect tissue for pathological examination. If the pathology report indicates endometrial cancer or precancerous lesions, then it will be reported. Therefore, endometrial thickening is not necessarily indicative of endometrial cancer, and it can occur with conditions like endometrial polyps or irregular endometrial hyperplasia. Treatment at this stage should be based on the pathological results. Thus, while endometrial thickening should be taken seriously, it is not necessarily cancerous.