During my diagnosis and treatment, I have encountered many terms and phrases that were unfamiliar to me and required a quick lookup. To make things easier for others navigating a breast cancer diagnosis, I wanted to compile a list of common breast cancer terms and define them in a clear, easy-to-understand way. If there are any additional words or phrases, you’d like me to include, please feel free to let me know.
Benign
A tumor that is not cancerous and does not spread.
BRCA
Short for BReast CAncer gene mutation. BRCA1 and BRCA2 mutations increase a person’s risk of developing breast and other cancers.
Biopsy
A procedure where a small sample of tissue, cells, or fluid is removed and tested to determine if cancer is present.
Chemotherapy
A cancer treatment that uses drugs to kill cancer cells or slow their growth. Because it travels through the bloodstream, it affects the whole body. Chemo can be given through an IV or as pills—both are equally effective.
Chemo Brain
A term used to describe memory issues, brain fog, or trouble concentrating that can happen during or after chemotherapy.
Dense Breasts
Breasts with more fibrous and glandular tissue than fat. Dense tissue can increase breast cancer risk and make mammograms harder to read.
Docetaxel
A chemotherapy drug in the taxane family used to treat several cancers, including breast cancer. It works by stopping cancer cells from dividing.
Ductal Carcinoma In Situ (DCIS)
A non-invasive breast cancer where abnormal cells are found only inside the milk ducts. DCIS is considered Stage 0 breast cancer.
Grade
A measure of how abnormal cancer cells look under a microscope.
- Grade 1 (Low): Slow growing
- Grade 2 (Intermediate): Moderate growth
- Grade 3 (High): Fast-growing and more likely to spread
Herceptin (Trastuzumab)
A targeted therapy drug used to treat HER2-positive breast cancer.
HER2
A protein that helps breast cells grow.
- HER2-positive / HER2-low: Higher-than-normal levels that can cause faster cancer growth; treated with targeted therapy
- HER2-negative: Normal levels; targeted HER2 therapies are not effective
Hormonal Therapy
Treatment that blocks estrogen or progesterone, hormones that can fuel some breast cancers. Not effective for triple-negative breast cancer.
In Situ
Latin for “in its original place.” Cancer that has not spread.
Inflammatory Breast Cancer (IBC)
A rare, aggressive form of breast cancer that affects the skin and lymph vessels of the breast. Often diagnosed at Stage 3.
Infusion
Medication delivered slowly into the body through a vein, commonly used for chemotherapy and targeted therapies.
Invasive Ductal Carcinoma (IDC)
The most common type of breast cancer. Cancer begins in the milk ducts and spreads into surrounding breast tissue.
Invasive Lobular Cancer (ILC)
Cancer that begins in the milk-producing lobules and can spread to nearby tissue and beyond.
Lobular Carcinoma In Situ (LCIS)
Not cancer, but a condition that increases future breast cancer risk. Often monitored closely and sometimes treated with hormone therapy.
Lumpectomy
Surgery that removes the tumor and a small margin of surrounding tissue while preserving most of the breast.
Lymphedema
Swelling caused by damage to the lymph system, often affecting the arm, breast, or chest after lymph node removal.
Malignant
Cancerous and capable of spreading.
Mammogram
An X-ray of the breast used to detect cancer.
- Screening mammogram: Routine check with no symptoms
- Diagnostic mammogram: More detailed imaging when something looks suspicious
Mastectomy
Surgical removal of one or both breasts. There are several types, including total, skin-sparing, nipple-sparing, and bilateral mastectomy.
Metastatic Breast Cancer (MBC)
Stage 4 breast cancer, meaning the cancer has spread to other parts of the body. While not curable, it is treatable.
Oncotype DX
A lab test that helps predict the chance of breast cancer recurrence and whether chemotherapy will be beneficial.
Palliative Care
Specialized care focused on relieving symptoms and improving quality of life, alongside active cancer treatment.
PET Scan
An imaging test that uses a tracer to help detect cancer spread throughout the body.
Preventative (Prophylactic) Mastectomy
Removal of one or both breasts to reduce cancer risk, often chosen by people with BRCA mutations.
Prognosis
A doctor’s estimate of how a disease may progress and respond to treatment.
Radiation
Treatment that uses high-energy rays to kill cancer cells in a specific area of the body.
Reconstruction
Surgery to rebuild the breast after mastectomy using implants or the patient’s own tissue.
Recurrence
Cancer that returns after treatment.
- Local: Same breast
- Regional: Nearby lymph nodes
- Distant: Spread to other organs (Stage 4)
Red Devil
Nickname for the chemotherapy drug doxorubicin, named for its red color and strong side effects.
Stage
Describes how large the cancer is and how far it has spread (Stages 0–4).
Tamoxifen
A hormone therapy drug taken for several years to reduce the risk of breast cancer recurrence.
Targeted Therapy
Treatment that attacks specific proteins on cancer cells to stop their growth.
Thriver
A term often used by people living with metastatic breast cancer to describe living fully with the disease.
Triple-Negative Breast Cancer (TNBC)
Breast cancer that lacks estrogen, progesterone, and HER2 receptors. Hormone therapy is ineffective; chemotherapy is the main treatment.
Tumor
A mass of abnormal cells that can be benign or malignant.
Ultrasound
An imaging test that uses sound waves to evaluate suspicious areas in the breast.