A friend of mine has HER2-positive breast cancer. Can you tell me what this means?

HER2-positive breast cancer is a breast cancer that tests positive for a protein called human epidermal growth factor receptor 2 (HER2). This protein promotes the growth of cancer cells.

In about 1 of every 5 breast cancers, the cancer cells have extra copies of the gene that makes the HER2 protein. HER2-positive breast cancers tend to be more aggressive than other types of breast cancer.

Treatments that specifically target HER2 are very effective. These treatments are so effective that the prognosis for HER2-positive breast cancer is actually quite good.

Certain standard chemotherapy drugs also can be effective in treating HER2-positive breast cancers, although these drugs don't specifically target the HER2 protein.

Experts recommend that every invasive breast cancer be tested for the presence of HER2 because the results significantly impact treatment recommendations and decisions. HER2 testing is not done routinely for ductal carcinoma in situ, except as part of a clinical trial.

Whenever breast cancer recurs or spreads, the cancer cells should be retested for HER2 as well as for hormone receptor status, as these can change from the original diagnosis.

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April 09, 2024 See more Expert Answers

See also

  1. 3D mammogram
  2. Accelerated partial breast irradiation (ABPI)
  3. Alternative cancer treatments: 11 options to consider
  4. Axillary (armpit) lymph node dissection
  5. Biopsy procedures
  6. Blood Basics
  7. Bone scan
  8. Brachytherapy
  9. BRCA gene test
  10. Breast cancer
  11. Breast Cancer
  12. Breast cancer chemoprevention
  13. Breast Cancer Education Tool
  14. Common questions about breast cancer treatment
  15. Breast cancer prevention
  16. Infographic: Breast Cancer Risk
  17. Breast cancer risk assessment
  18. Breast cancer staging
  19. Breast cancer supportive therapy and survivorship
  20. Breast cancer surgery
  21. Breast cancer types
  22. Breast cancer-related lymphedema
  23. Breast implants and cancer
  24. Evaluating breast lumps
  25. Breast lumps
  26. Breast MRI
  27. Breast reconstruction with flap surgery
  28. Breast reconstruction with implants
  29. Breast self-exam for breast awareness
  30. Cancer blood tests
  31. Cancer survivorship program
  32. Cancer treatment
  33. Chemo targets
  34. Chemotherapy
  35. Chemotherapy and hair loss: What to expect during treatment
  36. Chemotherapy and sex: Is sexual activity OK during treatment?
  37. Chemotherapy for breast cancer
  38. Chemotherapy nausea and vomiting: Prevention is best defense
  39. Chest X-rays
  40. Complete blood count (CBC)
  41. Contrast-enhanced mammography
  42. Coping with pain after breast surgery
  43. COVID-19 vaccine: Should I reschedule my mammogram?
  44. CT scan
  45. Dense breast tissue
  46. Does soy really affect breast cancer risk?
  47. Doppler ultrasound: What is it used for?
  48. Dragon Boats and Breast Cancer
  49. Flat aesthetic closure
  50. Genetic Testing for Breast Cancer
  51. Genetic testing for breast cancer: Psychological and social impact
  52. Hormone therapy for breast cancer
  53. Intralesional injection therapy
  54. Lumpectomy
  55. Magic mouthwash
  56. Mammogram
  57. Mammogram guidelines: What are they?
  58. Mastectomy
  59. What is breast cancer? An expert explains
  60. Minimally invasive inguinal lymphadenectomy (MILND)
  61. Modified radical mastectomy
  62. Molecular breast imaging
  63. MRI
  64. MRI-guided breast biopsy
  65. Nipple discharge
  66. Nipple-sparing mastectomy
  67. Oncoplastic breast-conserving surgery
  68. PALS (Pets Are Loving Support)
  69. Paulas story A team approach to battling breast cancer
  70. Pink Sisters
  71. Positron emission mammography (PEM)
  72. Positron emission tomography scan
  73. Precision medicine for breast cancer
  74. Prophylactic mastectomy
  75. Radiation therapy
  76. Radiation therapy for breast cancer
  77. Seeing inside the heart with MRI
  78. Sentinel node biopsy
  79. Skin-sparing mastectomy
  80. Stereotactic breast biopsy
  81. Support groups
  82. Surgical biopsy
  83. The Long Race Beating Cancer
  84. Thyroid guard: Do I need one during a mammogram?
  85. Tomosynthesis-guided breast biopsy
  86. Ultrasound
  87. Sentinel node biopsy for melanoma
  88. Mammogram for breast cancer — What to expect
  89. MRI
  90. Weight Loss After Breast Cancer
  91. X-ray