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Breast cancer is diagnosed in more than 250 000 people in the United States each year.
Diagnosis and Stages of Breast Cancer
Breast cancer occurs when cells in the breast begin to grow out of control. Many breast cancers are diagnosed based on a mammogram, a specialized x-ray scan designed to look closely at breast tissue. Some breast cancers are diagnosed when a woman or her doctor finds an abnormal lump in her breast. Rarely, changes in the skin or nipple of the breast can be the first sign of a breast cancer.
At diagnosis, breast cancer cells may be found in the breast tissue only, in the axillary lymph nodes under the arm, or in more distant sites in the body. Based on where the cancer is found, breast cancer is assigned a stage, from I to IV. Stage IV breast cancer, also called metastatic breast cancer, is breast cancer that has spread to a place in the body distant from the breast and axillary lymph nodes.
Types of Breast Cancer
Breast cancer is divided into 3 types based on the presence or absence of different proteins in the breast cancer cells. Hormone receptor–positive breast cancer makes up 70% of breast cancer cases and has either estrogen receptor (ER) or progesterone receptor (PR) protein in the cancer cells; ERBB2-positive (formerly known as HER2-positive) breast cancer makes up 15% to 20% of breast cancer cases and has high levels of ERBB2 protein on the cancer cells; and triple-negative breast cancer makes up 15% of breast cancer cases and does not have ER, PR, or ERBB2 protein in the cancer cells.
Prognosis and Treatment of Breast Cancer
Most people in the United States who have breast cancer diagnosed do not die of their breast cancer. Compared with the 250 000 cases diagnosed annually, 41 000 deaths due to breast cancer occur each year. The prognosis and treatment of breast cancer depend on the stage and the type of breast cancer.
Each treatment plan is individualized and should be made together by a patient and a cancer doctor. For patients with stage I to III breast cancer, the goal of treatment is to cure the breast cancer. Usual treatment consists of surgery to remove the breast tumor, medicines, and possibly radiation therapy to the breast. For patients with stage IV breast cancer, which has spread to a distant part of the body, the goal of treatment is to control the breast cancer for as long as possible. Treatment for stage IV breast cancer consists mainly of medicines.
Different types of breast cancer respond to different medicines. Hormone receptor–positive breast cancer is best treated with anti-estrogen pills. Some patients need intravenous chemotherapy infusions as well. ERBB2-positive breast cancer is treated with intravenous medicines that specifically attack the abnormal ERBB2 protein along with intravenous chemotherapy. Triple-negative breast cancer is treated with intravenous chemotherapy.
American Cancer Societywww.cancer.org/cancer/breast-cancer.html
National Comprehensive Cancer Networkwww.nccn.org/patients/guidelines/cancers.aspx
To find this and other JAMA Patient Pages, go to the For Patients collection at jamanetworkpatientpages.com.
Conflict of Interest Disclosures: Dr Winer reported personal fees from Genentech, Roche, Lilly, Tessaro, GlaxoSmithKline, Leap Pharmaceuticals, Carrick Therapeutics, and Jounce Pharmaceuticals and stock options from Verastem. No other disclosures were reported.
Waks AG, Winer EP. Breast Cancer Treatment. JAMA. 2019;321(3):316. doi:10.1001/jama.2018.20751
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