A friend of mine has HER2-positive breast cancer. Can you tell me what this means?
Answer From Karthik Giridhar, M.D.
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.
Karthik Giridhar, M.D.
April 07, 2020
Get the latest health information from Mayo Clinic’s experts.
Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health.
ErrorEmail field is required
ErrorInclude a valid email address
To provide you with the most relevant and helpful information, and understand which
information is beneficial, we may combine your email and website usage information with
other information we have about you. If you are a Mayo Clinic patient, this could
include protected health information. If we combine this information with your protected
health information, we will treat all of that information as protected health
information and will only use or disclose that information as set forth in our notice of
privacy practices. You may opt-out of email communications at any time by clicking on
the unsubscribe link in the e-mail.
Thank you for subscribing
Our Housecall e-newsletter will keep you up-to-date on the latest health information.
Sorry something went wrong with your subscription
Please, try again in a couple of minutes
See more Expert Answers
- Yamauchi H, et al. HER2 and predicting response to therapy in breast cancer. https://www.uptodate.com/contents/search. Accessed Feb. 23, 2020.
- Waks AG, et al. Breast cancer treatment: A review. JAMA. 2019; doi:doi:10.1001/jama.2018.19323.
- Ahn S, et al. HER2 status in breast cancer: Changes in guidelines and complicating factors for interpretation. Journal of Pathology and Translational Medicine. 2020;54:34.
- Giridhar K (expert opinion). Mayo Clinic. March 6, 2020.