Hello welcome to health care magic For your breast cancer you are using tamoxifen since sugery,, Tamoxifen is used in the treatment of estrogen receptor positive breast cancer.. But that tamoxifen has side effects like it causes endometrial polyp,endometrial hyperplasia and endometrial cancer.. Endometrial polyp causes slight bleeding..some of the polyps are carcinogenic.. so better consult Gynecologist and remove it by simple curettage..and the removed mass send to histopathology.. If cancerous cells are present then you have to undergo hysterectomy that is complete removal of uterus...as you are near menopause so no problems.. Hope you understand my suggestion Thank you Dr.siddartha