Glossary of medical terms

You may hear these common medical terms and phrases when talking with your healthcare team about HER2+ breast cancer


Adjuvant treatment

Treatment given after surgery.

Advanced breast cancer

The cancer may have spread from where it first started to nearby tissue, lymph nodes, or distant parts of the body.


Cancer cell

A cell that divides and reproduces abnormally with uncontrolled growth. This cell can break away, travel to other parts of the body, and then set up at another site. This process is referred to as metastasis.


A type of medication that kills cells that grow and divide rapidly, including cancer cells and normal cells.


Early breast cancer

When the cancer is located in only the breast or is in the breast and has only spread to nearby lymph nodes, but not to other parts of the body.


First-line treatment for cancer that has spread to other parts of the body

A treatment that is given first or as an initial treatment for cancer that is advanced or metastatic.


HER2-positive (HER2+)

HER2 stands for human epidermal growth factor receptor 2. When breast cancer cells have too many HER2 receptors, they are called HER2- positive, or HER2+ breast cancer.

HER2 receptor

A type of protein that is found on the surface of cells in everyone. This protein tells cells to grow and divide. Too much HER2 is called “HER2 overexpression” and may result in the cells growing and dividing more quickly.

Hormonal treatment

Helps fight tumors that thrive on hormones such as estrogen or progesterone by acting on hormone receptors on tumor cells or by decreasing the amount of hormones available to bind these receptors.

Hormone receptor

A protein on the edge or inside of cells to which hormones attach.


Immune system

Your body’s natural defense against infections and disease.

Intravenous infusion

Also known as an IV infusion, this is a way of delivering medication slowly into the bloodstream through a vein or port. Some medicines, such as KADCYLA, can only be given by IV infusion.


Locally advanced

Locally advanced breast cancer has not spread to distant parts of the body, but is large enough to affect breast skin and underlying chest structures. It can cause changes to breast shape and lymph node enlargement that is visible or can be felt in a breast exam.

Lymph nodes

Small, bean-shaped organs found throughout the body that store white blood cells and help remove cell waste, germs, and other harmful substances from the body.



When a cancer has metastasized, that means it has spread to other parts of the body.

Metastatic breast cancer

Breast cancer that has spread outside the breast to other parts of the body, such as the lungs, liver, or bones.

Monoclonal antibody

A type of protein made in the laboratory that binds to substances in the body such as a specific type of cancer cell, but may also affect some healthy cells. Monoclonal antibodies used to treat cancer can be used alone or to carry drugs or other substances directly to cancer cells.


Neoadjuvant treatment

Treatment given before surgery.


Pathology report

A report that details the results of a tissue exam conducted to determine the presence of disease. The pathology report can help healthcare teams determine how advanced the cancer is, how aggressive it is, and other unique characteristics that will help in making better treatment decisions.


An implanted device through which blood can be taken and medication can be given without repeated needle sticks; also called a “port-a-cath.”


Radiation treatment

Radiation treatment uses high-energy rays to kill cells and/or shrink tumors.

Residual disease

When cancer cells are present in surgically removed tissue, even after neoadjuvant treatment.


Second-line treatment

Treatment given when first-line treatment doesn’t work or stops working.


A type of cancer treatment that involves removing tumors and/or lymph nodes from the body. This can include a mastectomy (the removal of the entire breast) or lumpectomy (the removal of the tumor, as well as some surrounding normal tissue) for breast cancer.

Systemic disease

A disease that affects the whole body.


Targeted cancer treatment

A type of medication that targets specific characteristics of cancer cells and may also affect normal cells.


A type of chemotherapy drug (eg, paclitaxel, docetaxel) that stops the growth of cells and makes it difficult for cells to repair damage.


An abnormal mass or growth of tissue that occurs when cells divide too rapidly, in an uncontrolled way. Tumors that are malignant are known as cancer.