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

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  3. Alternative cancer treatments: 11 options to consider
  4. Biopsy procedures
  5. Blood Basics
  6. Bone scan
  7. Brachytherapy
  8. BRCA gene test
  9. Breast cancer
  10. Breast cancer chemoprevention
  11. Breast Cancer Education Tool
  12. Breast cancer prevention
  13. Breast cancer risk assessment
  14. Breast cancer staging
  15. Breast cancer supportive therapy and survivorship
  16. Breast cancer surgery
  17. Breast cancer types
  18. Breast implants and cancer
  19. Breast MRI
  20. Breast reconstruction with flap surgery
  21. Breast reconstruction with implants
  22. Breast self-exam for breast awareness
  23. Cancer blood tests
  24. Cancer treatment
  25. Chemo targets
  26. Chemotherapy
  27. Chemotherapy and hair loss: What to expect during treatment
  28. Chemotherapy and sex: Is sexual activity OK during treatment?
  29. Chemotherapy for breast cancer
  30. Chemotherapy nausea and vomiting: Prevention is best defense
  31. Chest X-rays
  32. Common questions about breast cancer treatment
  33. Complete blood count (CBC)
  34. Coping with pain after breast surgery
  35. COVID-19 vaccine: Should I reschedule my mammogram?
  36. CT scan
  37. Dense breast tissue
  38. Does soy really affect breast cancer risk?
  39. Doppler ultrasound: What is it used for?
  40. Dragon Boats and Breast Cancer
  41. Evaluating breast lumps
  42. Genetic Testing for Breast Cancer
  43. Genetic testing for breast cancer: Psychological and social impact
  44. Hormone therapy for breast cancer
  45. Infographic: Breast Cancer Risk
  46. Lumpectomy
  47. Magic mouthwash
  48. Mammogram
  49. Mammogram for breast cancer — What to expect
  50. Mammogram guidelines: What are they?
  51. Mastectomy
  52. Molecular breast imaging
  53. MRI
  54. MRI
  55. PALS (Pets Are Loving Support)
  56. Pink Sisters
  57. Positron emission tomography scan
  58. Precision medicine for breast cancer
  59. Pressurized intraperitoneal aerosol chemotherapy (PIPAC)
  60. Radiation therapy
  61. Radiation therapy for breast cancer
  62. Seeing inside the heart with MRI
  63. Sentinel node biopsy
  64. Sentinel node biopsy for melanoma
  65. Support groups
  66. The Long Race Beating Cancer
  67. Thyroid guard: Do I need one during a mammogram?
  68. Ultrasound
  69. Weight Loss After Breast Cancer
  70. What is breast cancer? An expert explains
  71. X-ray