Glossary — A

An adenoma is a benign (non-cancerous) growth that forms in gland-like tissue, including the breast. It is not cancer and does not spread to other parts of the body, though it may be checked to confirm what it is.

Adjuvant therapy is additional treatment given after the primary treatment, usually surgery, to destroy any cancer cells that may remain and reduce the risk of recurrence. It can include chemotherapy, radiation, hormone therapy, or targeted drugs.

Anemia is a condition in which you do not have enough healthy red blood cells or hemoglobin to carry oxygen to your body's tissues. It can leave you feeling tired, weak, or short of breath, and in women it is often linked to blood loss or low iron.

Angiography is an imaging technique that uses a special dye and X-rays or other scans to make blood vessels visible. It helps doctors see narrowing, blockages, aneurysms, or other vessel problems that might not show up otherwise.

An aortic aneurysm is a bulge or balloon-like swelling in the wall of the aorta, the large artery that carries blood from your heart to the rest of your body. It develops where the vessel wall has weakened, and it often causes no symptoms until it grows large.

An aromatase inhibitor is a type of medication that blocks the enzyme aromatase, which the body uses to make estrogen. By lowering estrogen levels, it slows or stops the growth of breast cancers that depend on estrogen to grow, and is used mainly after menopause.

Atherosclerosis is the slow buildup of fatty deposits, called plaque, inside the walls of your arteries. Over time this narrows and stiffens the vessels, reducing blood flow and raising the risk of heart attack, stroke, and other vascular problems.

Atypical ductal hyperplasia is a benign condition in which an unusual number of slightly abnormal cells build up inside a breast milk duct. It is not cancer, but it signals a higher-than-average risk of developing breast cancer later, so it is watched closely.

The axilla is the medical term for the armpit. It contains lymph nodes, blood vessels, and nerves, and because breast tissue drains into the lymph nodes here, the axilla is an important area when evaluating and treating breast cancer.

Axillary dissection is a surgical procedure that removes a group of lymph nodes from the armpit. It is used in breast cancer care to find out whether cancer has spread to the nodes and to remove affected nodes, which helps guide staging and treatment.