Women diagnosed with metastatic HER2-positive breast cancer lived longer if they had surgery to remove the primary tumor in the breast, according to a study.
The research was presented April 2, 2019, at the American Association for Cancer Research (AACR) Annual Meeting. Read the abstract of “The impact of primary tumor surgery on survival in HER2 positive stage IV breast cancer patients in the current era of targeted therapy.”
Metastatic breast cancer is cancer that has spread to parts of the body away from the breast, such as the bones or liver.
HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. HER2-positive breast cancers tend to be more aggressive and harder to treat than HER2-negative breast cancers.
According to the researchers who did this study, between 20% and 30% of all newly diagnosed metastatic breast cancer is HER2-positive.
How this study was done
Since the development of Herceptin (chemical name: trastuzumab) and other anti-HER2 targeted therapy medicines, most people diagnosed with HER2-positive breast cancer of any stage are treated with some combination of anti-HER2 targeted therapy, chemotherapy, and/or hormonal therapy, if the cancer is also hormone-receptor-positive.
Earlier research on whether adding surgery to targeted therapy improved survival in people diagnosed with metastatic HER2-positive breast cancer had mixed results. Also, many hospital systems did not document the effect of surgery on metastatic HER2-positive breast cancer.
So, the researchers conducted a retrospective study to see how surgery affected survival outcomes in women diagnosed with metastatic HER2-positive disease.
A retrospective study means that the researchers looked at information collected before the study was designed.
The study included 3,231 women diagnosed with metastatic HER2-positive breast cancer from 2010 to 2012. The information came from the National Cancer Database, a collection of data from more than 1,500 Commission on Cancer-accredited facilities. The database is sponsored by the American College of Surgeons and the American Cancer Society.
Of the women in the study:
- 71.3% were white
- 18.4% were black
- 5.8% were Hispanic
One-quarter of the women had metastatic breast cancer lesions only in their bones.
Treatment choices were:
- 89.4% of the women were treated with targeted therapy/chemotherapy
- 37.7% of the women were treated with hormonal therapy
- 31.8% of the women were treated with radiation
Overall, 1,130 women (35%) had surgery to remove the primary cancer tumor in the breast and 2,101 women (65%) did not have surgery to remove the primary cancer tumor.
Women who had surgery were, on average, younger (56 years old) than women who didn’t have surgery (59 years old).
Half the women were followed for more than 21.2 months and half the women were followed for shorter periods of time.
The researchers found that surgery was associated with a 44% increase in overall survival:
- overall survival was about 25 months for women who had surgery
- overall survival was about 18 months for women who didn’t have surgery
Overall survival is how long the women lived, whether or not the cancer grew.
Women who had surgery were more likely to:
- be younger
- have a lower income
- have private insurance or Medicare coverage
- be treated at a community cancer center
Other factors besides surgery linked to better survival were:
- older age
- Medicare insurance coverage
- being treated with targeted therapy/chemotherapy
“Surgery should be discussed with patients as an option that may provide longer survival when considered alongside targeted therapy and other standards of care,” said Ross Mudgway, third-year medical student at the University of California, Riverside, and the study’s lead author, at a media briefing at the AACR Annual Meeting.
Co-author Sharon Lum, M.D., professor and medical director of the Breast Health Center at Loma Linda University, added, “[the study] suggests that, in addition to standard HER2-targeted medications and other adjuvant therapy, if a woman has stage IV HER2-positive breast cancer, surgery to remove the primary breast tumor should be considered.”
What this means for you
It’s important to remember two things about this study:
- This study was a retrospective study, so the data were collected before the study was designed. Many researchers feel a retrospective study is not as strong as a prospective study, where the study is designed and then the data are collected.
- The women who had surgery were younger than the women who didn’t have surgery. This age difference could have affected the survival results.
For both of these reasons, the study results should be interpreted with caution.
If you’ve been diagnosed with metastatic HER2-positive breast cancer, you and your doctor will consider a number of treatment options, including anti-HER2 targeted therapy medicines and chemotherapy. If surgery is not recommended for you, you may want to bring up this study and talk to your doctor about why surgery isn’t in your treatment plan.
Together, you and your doctor will develop the best treatment plan for your unique situation.
For more information on metastatic breast cancer treatments, visit the Breastcancer.org Metastatic Breast Cancer pages.
To talk with others who have been diagnosed with metastatic breast cancer, join the Breastcancer.org Discussion Board forum Stage IV/Metastatic Breast Cancer ONLY.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser