Breast Cancer Glossary of Terms

April 16, 2020


Absolute risk
Risk is the chance that something will happen to you during a certain period of time. It is the number of people who would have the event if 100 people were observed. It is written as a percent (%). For instance, your risk of getting a disease in the next 5 years might be 3%. If you have the disease, your risk of dying from it in the next 10 years might be 20%. Your risk is based on studies of people who are similar to you.

Additional cancer treatment given after the primary treatment (usually surgery) to lower the risk that the cancer will come back. Adjuvant therapy may include chemotherapy, radiation therapy, hormone therapy, targeted therapy, or biologic therapy.

Blood vessel formation. Tumor angiogenesis is the growth of new blood vessels that tumors need to grow. This is caused by the release of chemicals by the tumor.

A noninvasive condition in which abnormal cells are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. In some cases, DCIS may become invasive cancer and spread to other tissues, although it is not known at this time how to predict which lesions will become invasive. Also called ductal carcinoma in situ and intraductal carcinoma.

Disease free survival  (also referred to as event-free survival)
This is the time from the beginning of an intervention until a patient experiences a recurrence, a new primary cancer or death.

In clinical trials, an event or outcome that can be measured objectively to determine whether the intervention being studied is beneficial. The endpoints of a clinical trial are usually included in the study objectives. Some examples of endpoints are survival, improvements in quality of life, relief of symptoms, and disappearance of the tumor.

Initial treatment used to reduce a cancer. First-line therapy is followed by other treatments, such as chemotherapy, radiation therapy, and hormone therapy to get rid of cancer that remains. Also called induction therapy, primary therapy, and primary treatment.

Gene amplification
An increase in the number of copies of a gene. There may also be an increase in the RNA and protein made from that gene. Gene amplification is common in cancer cells, and some amplified genes may cause cancer cells to grow or become resistant to anticancer drugs. Genes may also be amplified in the laboratory for research purposes.

HER2 is short for Human Epidermal Growth Factor Receptor 2 (also be called Her-2/neu or ErbB2). All normal breast cells contain copies of the HER2 gene, which gives instructions to the cell on how to make the HER2 protein.  The HER2 protein, also called the HER2 receptor, is found on the surface of normal cells. These proteins help send signals to the inside of the cell telling it to grow and divide. In HER2-positive breast cancer, there are extra copies of the HER2 gene (amplification), leading to extra HER2 protein (overexpression). Too much HER2 protein is thought to cause cancer cells to grow and divide more quickly.

Invasive breast cancer
Abnormal cells that have invaded neighboring tissues. The two most common types are:

Invasive Ductal Carcinoma
Starting in a milk passage, or duct, of the breast, the cancer cells break through the wall of the duct and invade the breast’s fatty tissue. They can then invade into lymphatic channels or blood vessels of the breast and spread to other parts of the body. Infiltrating or invasive ductal carcinoma accounts for about 80 percent of all breast cancers.

Invasive Lobular Carcinoma
This type of cancer starts in the milk-producing glands (lobules). Like IDC, this cancer can spread beyond the breast to other parts of the body. About 10 to 15 percent of invasive breast cancers are invasive lobular carcinomas.

Lymph Node
A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph nodes filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called lymph gland.

Results from individual published research studies are pooled together and their collective findings summarized.

The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a “metastatic tumor” or a “metastasis.” The metastatic tumor contains cells that are like those in the original (primary) tumor.

Monoclonal antibody
A type of protein made in the laboratory that can bind to substances in the body, including tumor cells. There are many kinds of monoclonal antibodies. Each monoclonal antibody is made to find one substance. Monoclonal antibodies are being used to treat some types of cancer and are being studied in the treatment of other types. They can be used alone or to carry drugs, toxins, or radioactive materials directly to a tumor.

Overall survival (OS)
The percentage of people in a study or treatment group who are alive for a certain period of time after they were diagnosed with or treated for a disease, such as cancer. The overall survival rate is often stated as a five-year survival rate, which is the percentage of people in a study or treatment group who are alive five years after diagnosis or treatment. Also called survival rate.

A doctor who identifies diseases by studying cells and tissues under a microscope.

Primary treatment
Initial treatment used to reduce a cancer. Primary treatment is followed by other treatments, such as chemotherapy, radiation therapy, and hormone therapy to get rid of cancer that remains. Also called first-line therapy, induction therapy, and primary therapy.

Progression-free survival
The length of time during and after treatment in which a patient is living with a disease that does not get worse. Progression-free survival may be used in a clinical study or trial to help find out how well a new treatment works. Also called PFS.

In medicine, a study or clinical trial in which participants are identified and then followed forward in time.

A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin and hair and of substances such as enzymes, cytokines, and antibodies.

Randomization is when people in a clinical trial are randomly assigned to treatment groups by chance, like flipping a coin. The investigators running the study do not decide who gets which treatment.

Relative risk
A measure of the risk of a certain event happening in one group compared to the risk of the same event happening in another group. In cancer research, relative risk is used in prospective (forward looking) studies, such as cohort studies and clinical trials. A relative risk of one means there is no difference between two groups in terms of their risk of cancer, based on whether or not they were exposed to a certain substance or factor, or how they responded to two treatments being compared. A relative risk of greater than one or of less than one usually means that being exposed to a certain substance or factor either increases (relative risk greater than one) or decreases (relative risk less than one) the risk of cancer, or that the treatments being compared do not have the same effects. Also called risk ratio.

Looking back at events that have already taken place.

Treatment that is given when initial treatment (first-line therapy) doesn’t work, or stops working.

Statistically significant
Describes a mathematical measure of difference between groups. The difference is said to be statistically significant if it is greater than what might be expected to happen by chance alone. Also called significant.

Targeted cancer therapies
A type of treatment that uses drugs or other substances, such as monoclonal antibodies, to identify and attack specific cancer cells. Targeted therapy may have fewer side effects than other types of cancer treatments.