The Mysterious A-B-Cs of Breast Cancer: 15 Confusing Terms You Might Not Know (and Should)

Patient Expert

You or a loved one has just been diagnosed with breast cancer. The doctor says the cancer is ER/PR+, and your first treatment will be neoadjuvant. What? Get up to speed fast with these 15 must-know breast cancer terms.


Adjuvant treatment is given after the main treatment for breast cancer (usually surgery). Chemotherapy, radiation, and hormone therapy are all examples of adjuvant treatment. Neoadjuvant refers to these same treatments when they’re delivered before surgery — e.g., chemotherapy to shrink a tumor prior to it being removed.


When used in connection with breast surgery, this refers to breast reconstruction using part of the patient’s own body, rather than a silicone implant.

Axillary dissection

Surgery to remove and examine lymph nodes from under the patient’s arm on the same side as the breast tumor. This is done to determine whether or not cancer has spread outside the breast.


The scientific name for cancer.

Complementary therapy/alternative therapy

Complementary therapy is non-drug treatment to help alleviate the side effects of cancer treatment. Examples include Reiki, therapeutic massage, and meditation. Alternative therapy is cancer treatment without the scientific backing that would make it an option for the typical physician, e.g., following a macrobiotic diet or cleansing.

ER/PR +/-

Translation: estrogen/progesterone positive or negative. Most breast cancers are dependent on the female sex hormones estrogen and/or progesterone for growth. ER/PR-positive cancers are treated with long-term hormone therapy to reduce risk of recurrence; negative cancers don’t respond to hormone therapy.


Pathologists grade breast cancer cells 1 through 3, with 1 being the closest to normal/least aggressive, and 3 being most abnormal/aggressive. A cancer’s grade, which will be listed in the patient’s pathology report, helps determine type of treatment.


About 25 percent of all breast cancers are termed HER-2/neu positive (Her2+). This type of cancer is more serious, and thus requires more aggressive treatment. Along with surgery, the patient will typically have chemotherapy and possibly radiation; and will probably take the drug Herceptin (trastuzumab) for a year.

Infiltrating, invasive, in situ

Cancer cells that have broken through the walls of the breast duct or lobule where they first formed, spreading into surrounding tissue, are called infiltrating or invasive. Before those cells spread, they’re termed in situ.

Local, regional, distant

These terms refer to where breast cancer might recur. A local recurrence is in the same breast as the original cancer. A regional recurrence is in the lymph nodes on the same side of the body as the first tumor. A distant recurrence is the same as metastasis: cancer that has left the breast/underarm, and traveled to another part of the body.


A possible side effect of both radiation and lymph node removal, this long-term (and potentially dangerous) condition is characterized by swelling of the arm and trunk nearest the affected breast.


Breast cancer that’s left the breast and underarm lymph nodes, and recurred elsewhere in the body, most often in the lungs, bones, liver, or brain.

Oncotype DX test

A genetic test that examines a breast cancer tumor to determine how likely cancer is to recur after surgery, and thus how important it is to have chemotherapy. The lower the score, the less likely cancer is to recur, the less critical it is for a patient to undergo chemo.


A personally fitted form, usually silicone, that slips into a specialty bra to replace the shape and weight of a breast lost to mastectomy.

Sentinel node

The lymph node closest to a tumor, and the first node cancer might spread to. The surgeon will sample tissue from a patient’s sentinel node to see whether the cancer has spread beyond its original site.


A breast cancer diagnosis report will include a stage (1-4), and possibly sub-stage (e.g., 3b). The patient’s oncologist will determine the stage of cancer based in large part on the pathology report from her biopsy. Stage determines the type of treatment delivered; stage 1 is least serious, stage 4 most serious.

See More Helpful Articles:

A Guide to Breast Cancer Symptoms

Just Diagnosed? We Can Help

A Guide to Breast Cancer Treatment

Breast Cancer: Relieving Stress, One Step at a Time

Breast cancer survivor and award-winning author PJ Hamel, a long-time contributor to the HealthCentral community, counsels women with breast cancer through the volunteer program at her local hospital. She founded and manages a large and active online survivor support network.