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What are HER2-positive and HER2-negative breast cancers?

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HER2-negative and HER2-positive are types of breast cancer that share some things in common, but they have plenty of differences, too. Which kind you have can affect the treatment you get.

Cancer is uncontrolled cell growth. Breast cancer means these cells started in the breast, though they may spread to nearby tissue and organs and eventually to anywhere in the body.

HER2 stands for human epidermal growth factor receptor-2. It's healthy in normal amounts, but too much may be a sign of a certain type of breast cancer.

Most people with breast cancer have a normal amount of this protein, which means you are HER2-negative. But about 1 in 5 cases are HER2-positive, which means your levels are unusually high.

If you have breast cancer, your doctor will likely test your HER2 to figure out if you're "negative" or "positive."

SOURCES:

American Cancer Society: "Targeted Therapy for Breast Cancer," "Treatment of Breast Cancer by Stage," "Breast Cancer Grades," "Survival Rates for Breast Cancer," "Breast Cancer HER2 Status."

American Joint Committee on Cancer: "Physician to Physician AJCC 8th Edition Breast."

American Society of Clinical Oncology: "Breast Cancer - Metastatic: Statistics."

Breastcancer.org: "HER2 Status," "Breast Cancer Stages."

Mayo Clinic: "HER2-positive breast cancer: What is it?"

University of Rochester Medical Center: "Breast Cancer: Grades and Stages."

Reviewed by Melinda Ratini on May 26, 2020

SOURCES:

American Cancer Society: "Targeted Therapy for Breast Cancer," "Treatment of Breast Cancer by Stage," "Breast Cancer Grades," "Survival Rates for Breast Cancer," "Breast Cancer HER2 Status."

American Joint Committee on Cancer: "Physician to Physician AJCC 8th Edition Breast."

American Society of Clinical Oncology: "Breast Cancer - Metastatic: Statistics."

Breastcancer.org: "HER2 Status," "Breast Cancer Stages."

Mayo Clinic: "HER2-positive breast cancer: What is it?"

University of Rochester Medical Center: "Breast Cancer: Grades and Stages."

Reviewed by Melinda Ratini on May 26, 2020

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How does having HER2-positive breast cancer affect the kind of treatment you get?

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