Questions and answers: Breast implant and mammography study
- What was the purpose of the study?
- What did the study find?
- Why doesn't mammography detect cancer as well in women with implants?
- Why is there so little difference in tumor characteristics among women with implants who develop breast cancer and women without implants who develop breast cancer?
- How was the study conducted?
- What are the strengths of this study?
- What's the bottom line for women with breast implants?
- What's the bottom line for women considering implants?
- How common is breast augmentation?
- Who conducted the study?
- Who funded the study?
Q. What was the purpose of the study?
The researchers wanted to find out whether breast implants interfere with the detection of breast cancer and thereby delay cancer diagnosis, which could be harmful to women if this results in diagnosis of a more advanced cancer.
To do this, the researchers compared the accuracy of screening mammography between two groups—women with implants and women without implants, and compared their cancer characteristics, such as tumor stage and size.
- Breast implants decrease the ability of mammography to detect breast cancer. Screening mammography missed 55 percent of breast cancers in women with implants compared to only 33 percent among women without implants.
- Although mammography does not find cancer as well in women with implants, this does not seem to result in more advanced cancers at diagnosis. The study found that women with implants were diagnosed with cancers of similar stage and size as women without implants.
- Even among women with implants who had breast symptoms such as a breast lump, the tumors were not more advanced. In fact, among the subset of women with symptoms, women with implants had smaller tumors than women without implants.
- Breast implants do not cause more false-positive mammography results compared to women without implants. Thus, augmented women without cancer do not have more positive mammograms that result in additional procedures than non-augmented women without cancer.
Q. Why doesn't mammography detect cancer as well in women with implants?
The breast implant shows up as a solid white mass on the mammography film, blocking the view of the breast tissue.
Even when mammography technologists use a special technique called implant displacement views, which attempts to move the implant out of the way, there is still breast tissue that can't be seen on the mammogram.
Q. Why is there so little difference in tumor characteristics among women with implants who develop breast cancer and women without implants who develop breast cancer?
The answer is not clear. The researchers suggest it may be easier for women with implants to detect cancers missed by mammography because they often have less of their own breast tissue or because the implant provides a firm platform to press against, which may make the tumors more noticeable. Women with breast implants are told to check their breasts often for any problems with the implant, so they may be more likely to find lumps on their own. Or women with implants may be more body conscious and seek medical advice more quickly if they have a symptom.
Q. How was the study conducted?
Data on more than 1.7 million women who had mammograms was collected from seven mammography registries across the United States that participate in the NCI-funded Breast Cancer Surveillance Consortium.
From these, the researchers found 137 women with implants who had breast cancer, and they matched them with 685 women without implants who had breast cancer.
After determining which women had a screening mammogram within a year of breast cancer diagnosis, the researchers calculated the proportion of those who had breast cancer detected by mammography. This allowed them to determine that mammography was more likely to miss cancers in women with implants.
In addition, the researchers looked at cancer characteristics, such as tumor stage and size, and found no difference between women with and without implants.
Q. What are the strengths of this study?
- This is the first study to look at the accuracy of screening mammography in women with breast implants who do not have breast symptoms. Previous studies looked at mammography among women with implants who already had breast symptoms.
- This is the largest study and the only recent study to compare cancer characteristics among women with and without implants. Previous studies relied on data from the 1970s and 1980s, before screening mammography was routinely used. Data from this study comes from breast cancers diagnosed between 1995 and 2002.
Q. What's the bottom line for women with breast implants?
If you have breast implants you should:
- Be aware that mammography is less sensitive for women with implants. However, you should still get regular mammograms. In this study, mammography did catch 45 percent breast cancers in women with implants, and mammography is the best method for early detection of breast cancer.
- However, you should not be reassured by a normal mammogram result if you have breast symptoms. You should contact your physician right away if you find a lump or detect other problems with your breasts. This is true for all women. If you feel a lump, you should call your doctor—even if you've had a recent mammogram.
- Go to a mammography facility that has experience with implants.
- Tell the mammography staff about your implants when they schedule the exam so the staff can plan to perform additional imaging using a technique called implant displacement views, which moves the implant out of the way to allow a better view of the breast tissue.
Q. What's the bottom line for women considering implants?
If you're considering breast implants you should:
- Discuss the pros and cons with your personal physician.
- Be aware that breast implants could interfere with the ability of a mammogram to detect cancer.
Q. How common is breast augmentation?
- Breast implants are the third most common type of cosmetic surgery, after nose reshaping and liposuction.
- More than 260,000 women in the United States received breast implants for cosmetic reasons in 2002.
- Breast implant surgery is on the rise, increasing by 11 percent between 2000 and 2002.
The study was conducted by the Breast Cancer Surveillance Consortium, which includes researchers from seven mammography registries nationwide in Colorado, New Hampshire, New Mexico, North Carolina, San Francisco, Seattle, and Vermont.
Group Health Center for Health Studies (CHS) serves as the Statistical Coordinating Center for this consortium. Diana Miglioretti, PhD, an investigator at CHS, was the lead author of the study.
The National Cancer Institute.
Group Health Center for Health Studies
Founded in 1947, Group Health Cooperative is a Seattle-based, consumer-governed, nonprofit health care system. The Group Health Center for Health Studies is Group Health’s research institute. For 25 years, the Center has conducted nonproprietary public-interest research on preventing, diagnosing, and treating major health problems. Government and private research grants provide its main funding.