Uterine fibroids, also called leiomyomas, fibromyomas, or myomas, are the commonest non-cancerous tumors in women of childbearing age. Uterine fibroids grow from the smooth muscle tissue of the uterus and may vary in size from tiny seedlings to massive lumps that can distort and expand the uterus. They may be single or multiple, very often producing no symptoms at all, and are almost never associated with increased risk of developing cancer.