A tumorA mass of cells that can be benign or malignant. that grows, or grows more rapidly, in the presence of estrogenA female sex hormone that is primarily produced by the ovaries. Its primary function is to regulate the menstrual cycle and assist in the production of secondary sex characteristics such as breasts. It may even play a role in the production of cancer cells in the breast tissue.. Considered a positive indicator, as it permits hormonal treatment for control of the tumor, thus increasing options for the treatment.
