Breast cancer is a disease in which malignant cancer cells form in the tissues of the breast.

  • Ductal carcinoma is the most common type of breast cancer and begins in the cells of the ducts.
  • Lobular carcinoma is cancer that begins in the lobes or lobules and is more often found in both breasts than are other types of breast cancer.
  • Inflammatory breast cancer is an uncommon type of breast cancer in which the breast is warm, red, and swollen.

Breast cancer is the most common type of cancer among women in the United States other than skin cancer and is second only to lung cancer as a cause of cancer death in American women.

An estimated 234,190 new cases of invasive breast cancer are diagnosed each year. Over the past several years, however, deaths from breast cancer have decreased a little bit every year as cancer prevention, detection and treatment options have improved.

The UC Davis Breast Cancer Program provides comprehensive, multidisciplinary care for patients with all stages of breast cancer. Breast cancer patients have access to numerous clinical trials of new innovative therapies. Patients receive all of their care in one location, from a team of top academic physicians.

cells UC Davis Comprehensive Cancer Center recommends that women have regular clinical breast exams and mammograms to help find breast cancer early. Treatment is more likely to work well when breast cancer is detected early.

Clinical breast exam

During a clinical breast exam, your doctor looks for differences in size or shape between your breasts and checks for rashes, dimpling, or other abnormal signs. Using the pads of the fingers to feel for lumps, your doctor will check your entire breast, underarm, and collarbone area. A lump is generally the size of a pea before anyone can feel it. The exam is done on one side and then the other. Your doctor will also check the lymph nodes near the breast to see if they are enlarged.

If you have a lump, your doctor will feel its size, shape, and texture and check to see if the lump moves easily. Benign lumps often feel different from cancerous ones. Lumps that are soft, smooth, round, and movable are likely to be benign. A hard, oddly shaped lump that feels firmly attached within the breast is more likely to be cancer, but further tests are needed to diagnose the problem.


A mammogram is an x-ray picture of tissues inside the breast. Mammograms can often show a breast lump before it can be felt. They also can show a cluster of tiny specks of calcium. These specks are called microcalcifications. Lumps or specks can be from cancer, precancerous cells, or other conditions. Further tests are needed to find out if abnormal cells are present.

Before they have symptoms, women should get regular screening mammograms to detect breast cancer early:

  • Women in their 40s and older should have mammograms every 1 or 2 years. 
  • Women who are younger than 40 and have risk factors for breast cancer should ask their health care provider whether to have mammograms and how often to have them.

If the mammogram shows an abnormal area of the breast, your doctor may order clearer, more detailed images of that area.

Other imaging tests

If an abnormal area is found during a clinical breast exam or with a mammogram, the doctor may order other imaging tests, including:

  • Ultrasound — An ultrasound device sends out sound waves that bounce off breast tissues. A computer uses the echoes to create a picture. The picture may show whether a lump is solid, filled with fluid (a cyst ), or a mixture of both. Cysts usually are not cancer. But a solid lump may be cancer. 
  • MRI — MRI (Magnetic Resonance Imaging) uses a powerful magnet linked to a computer to make detailed pictures of breast tissue. These pictures can show the difference between normal and diseased tissue.


A biopsy is the removal of tissue to look for cancer cells. You may need to have a biopsy if an abnormal area is found. Your doctor or a surgeon will remove fluid or tissue from your breast in one of several ways:

  • Fine-needle aspiration biopsy — Your doctor uses a thin needle to remove cells or fluid from a breast lump. 
  • Core biopsy — Your doctor uses a wide needle to remove a sample of breast tissue. 
  • Skin biopsy — If there are skin changes on your breast, your doctor may take a small sample of skin. 
  • Surgical biopsy — Your surgeon removes a sample of tissue.

Sources: National Cancer Institute and UC Davis Comprehensive Cancer Center 

Early breast cancer usually doesn't cause symptoms. But as the tumor grows, it can change how the breast looks or feels. The common changes include:

  • A lump or thickening in or near the breast or in the underarm area
  • A change in the size or shape of the breast
  • Dimpling or puckering in the skin of the breast
  • A nipple turned inward into the breast
  • Discharge (fluid) from the nipple, especially if it's bloody
  • Scaly, red, or swollen skin on the breast, nipple, or areola (the dark area of skin at the center of the breast). The skin may have ridges or pitting so that it looks like the skin of an orange.

If you have any of these symptoms, you should tell your doctor so that the problems can be diagnosed and treated.

Sources: National Cancer Institute and UC Davis Comprehensive Cancer Center 

No one knows the exact causes of breast cancer. People who think they may be at risk should discuss this with their doctor. Risk factors for breast cancer include the following:

  • Older age
  • Menstruating at an early age
  • Older age at first birth or never having given birth
  • A personal history of breast cancer or benign (non-cancer) breast disease
  • A mother or sister with breast cancer
  • Treatment with radiation therapy to the breast/chest
  • Breast tissue that is dense on a mammogram
  • Taking hormones such as estrogen and progesterone
  • Drinking alcoholic beverages
  • Being white

Sources: National Cancer Institute and UC Davis Comprehensive Cancer Center 


Most patients with breast cancer have surgery to remove the cancer. Types of surgery include:

Breast-conserving surgery — Surgery to remove the cancer and some normal tissue around it, but not the breast itself. Part of the chest wall lining may also be removed if the cancer is near it.

This type of surgery may also be called lumpectomy, partial mastectomy, segmental mastectomy, quadrantectomy, or breast-sparing surgery.

Modified radical mastectomy — Surgery to remove the whole breast that has cancer, many of the lymph nodes under the arm, the lining over the chest muscles, and sometimes, part of the chest wall muscles. This type of surgery is most common in pregnant women.

Total mastectomy — Surgery to remove the whole breast that has cancer. This procedure is also called a simple mastectomy. Some of the lymph nodes under the arm may be removed and checked for cancer. This may be done at the same time as the breast surgery or after. This is done through a separate incision.

More about surgical interventions for breast cancer

Radiation therapy

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. The way the radiation therapy is given depends on the type and stage of the cancer being treated.

External radiation therapy uses a machine outside the body to send radiation toward the cancer.

Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer.


Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing. The way the chemotherapy is given depends on the type and stage of the cancer being treated.

Systemic chemotherapy — When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body.

Regional chemotherapy — When chemotherapy is placed directly into the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas.

Hormone therapy

Hormone therapy is a cancer treatment that removes hormones or blocks their action and stops cancer cells from growing. Hormones are substances made by glands in the body and circulated in the bloodstream. Some hormones can cause certain cancers to grow. If tests show that the cancer cells have places where hormones can attach (receptors), drugs, surgery, or radiation therapy is used to reduce the production of hormones or block them from working.

The hormone estrogen, which makes some breast cancers grow, is made mainly by the ovaries. Treatment to stop the ovaries from making estrogen is called ovarian ablation.

Targeted therapy

Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells without harming normal cells. Monoclonal antibodies, tyrosine kinase inhibitors, cyclin-dependent kinase inhibitors, mammalian target of rapamycin (mTOR) inhibitors, and PARP inhibitors are types of targeted therapies used in the treatment of breast cancer.

Clinical trials

UC Davis Comprehensive Cancer Center has a large clinical trials network. The close collaboration between our doctors and our research scientists allows our patients access to the newest drugs and therapies before they become widely available. 

During all stages of your treatment you should talk to your oncologist about what clinical trials may be available for your type of breast cancer.

Other clinical services

Pathology and Laboratory Medicine

The UC Davis Medical Center Clinical Laboratory is home to one of the most technologically advanced laboratories in California, providing diagnostic pathology and testing not always available in the region. The laboratory provides services 24 hours per day 7 days per week in direct support of all the hospital inpatient areas.

Breast reconstruction surgery

Diagnostic radiology/mammography

Genetic counseling

Sources: National Cancer Institute and UC Davis Comprehensive Cancer Center 

Hematology and Oncology

Mili Arora, M.D.Mili Arora, M.D.
Associate Professor of Internal Medicine, Hematology and Oncology
Associate Director, Fellowship Program

Helen Chew, M.D.Helen Chew, M.D.
Professor of Internal Medicine, Hematology and Oncology
Director, Clinical Breast Cancer Program
Director, Fellowship Program

Scott Christensen, M.D.Scott Christensen, M.D.
Professor of Internal Medicine, Hematology and Oncology
Associate Director, Hospice Program

Kendra Hutchinson, M.D.Kendra Hutchinson, M.D.
Professor of Internal Medicine, Hematology and Oncology

Tianhong Li, M.D., Ph.D.Tianhong Li, M.D., Ph.D.
Professor of Internal Medicine, Hematology and Oncology

Eve Rodler, M.D.Eve Rodler, M.D.
Adjunct Associate Professor of Internal Medicine, Hematology and Oncology

Surgical Oncology

Richard Bold, M.D.Richard Bold, M.D.
Chief of Surgical Oncology
Professor of Surgery

Candice Sauder, M.D., M.Ed.Candice Sauder, M.D., M.Ed.
Assistant Professor of Surgery

Diagnostic Radiology

Shadi Aminololama-Shakeri, M.D.Shadi Aminololama-Shakeri, M.D.
Associate Professor

Cyrus Bateni, MDCyrus Bateni, M.D.
Assistant Professor

Karen Lindfors, M.D., M.P.H.Karen K. Lindfors, M.D.
Professor of Clinical Radiology


Alexander Borowsky, M.D.Alexander Borowsky, M.D.
Professor of Medical Pathology

Lydia Howell, M.D.Lydia P. Howell, M.D.
Chair and Professor of Pathology,
Department of Pathology and Laboratory Medicine

Plastic and Reconstructive Surgery

Lee Pu, M.D., Ph.D.Lee L.Q. Pu, M.D.
Professor of Surgery

David Sahar, M.D.David Sahar, M.D.
Associate Professor

Granger Wong, D.M.D., M.D.Granger Wong, D.M.D., M.D.
Associate Professor of Surgery

Radiation Oncology

Megan Daly, M.D.Megan Daly, M.D.
Assistant Professor


Danielle BahamDanielle Baham, M.S., R.D.

Kathleen NewmanKathleen Newman, R.D., C.S.O.

Genetic Counselors

Kellie BrownKellie Brown, M.Sc., L.G.C.

Nicole Mans, M.S., L.C.G.C.Nicole Mans, M.S., L.C.G.C.

Daniela Martiniuc, M.S.Daniela Martiniuc, M.S.

Jeanna Welborn, M.D.Jeanna Welborn, M.D.

Social Workers

Sara Chavez, LCSW, OSW-C, ACHP-SWSara Chavez, L.C.S.W., O.S.W.-C., A.C.H.P.-S.W.

Angela Usher, LCSW, OSW-CAngela Usher, L.C.S.W., O.S.W.-C.