Anovulatory menstrual cycle ​	A menstrual cycle that does not produce an egg, thereby producing lower estrogen ​  levels in a woman's body.
Arimidex ​	​  Example of a drug which blocks the aromatase enzyme. ​
Aromatase ​	​  The enzyme responsible for estrogen production present in the ovaries and also in ​  fat tissue.
​Atypical ductal hyperplasia ​	Overgrowth of abnormal cells within a milk duct (see diagram on page 9). ​
BRCA gene ​	​  A defective gene which can be inherited from a parent, increasing the risk of breast ​  cancer.
Cancer promoter ​	​An agent which stimulates cancer cells to grow faster. ​
Carcinogen or cancer initiator ​	​  An agent which causes a normal cell to transform into a cancer cell. ​
DHEA ​ ​	​  Dehydroepiandrosterone, an inactive adrenal product which declines with age. It   can be converted to estrogen in bone and vaginal lining, and can be used to treat ​  menopausal symptoms.
Differentiation ​	​  The maturing of cells from immature cancer susceptible cells to mature cancer ​  resistant cells.
DIM ​	​  Diindolylmethane, a metabolite of indole-3-carbinol (from cruciferous vegetables) ​  which aids in the inactivation of estrogen.
Estrogen ​	The main type of female sex steroid hormone primarily responsible for breast ​  growth.
Estrogen receptor ​	​  Place in cell where estrogen can attach, thereby stimulating the cell to grow or ​  change.
Gene ​	​  A portion of DNA in the nucleus of a cell which controls an inheritable trait. ​
Hyperplasia ​	​  Overgrowth of normal cells (see diagram on page 9). ​
​ Induced abortion ​	Termination of pregnancy by surgery or medication. ​
Lobule ​	Group of breast cells, composed of a duct and glands, which make milk. ​
​ Mammogram ​	A soft-tissue x-ray of the breast used to detect breast cancers. ​
​ Maturation of breast lobules ​	​  The development of lobules from primitive, immature cell structures present at   birth, which are incapable of producing milk and are most susceptible to   carcinogens, into advanced, mature cells which are capable of producing milk and ​  are most resistant to carcinogens.
Menarche ​	Age at which menstrual periods start. ​
​ Menopause ​	Age when menstrual periods stop. ​
Metabolism	​  Mechanism by which the body changes, processes and eliminates hormones and ​  other body chemical substances; i.e., turns them into metabolites.
Miscarriage ​	​  The spontaneous, natural loss of a pregnancy. ​
Mitogen ​	​  An agent that causes mitosis. ​
Mitosis ​	​  The process of cell division causing one cell to become two cells. ​
Natural Family Planning (NFP) ​	​  Any of several methods whereby a woman learns to recognize her own bodily   changes so that she recognizes the few days of fertility in her menstrual cycle (e.g., ​  type of cervical mucus and basal temperature). NFP is not the "rhythm method."
Nulliparous ​	​  Never bearing children. ​
​ Perimenopause ​	​  Years immediately preceding menopause, when menstrual periods can be irregular. ​
Progesterone ​	​  The steroid hormone which enables and maintains pregnancy, and permits the ​  mitogenic effect of estrogen.
Progestin ​	​  Any substance that acts like progesterone. ​
Proliferation ​	The multiplication of cells through mitosis. ​
Proliferative breast disease ​	​Breast tissue which has "overgrown," e.g., ductal hyperplasia which as multiple ​  layers of cells instead of a single layer.
​ Spontaneous abortion ​	Natural miscarriage not caused by surgery or drugs. ​
Tamoxifen ​	​  Example of a drug which blocks estrogen receptors. ​