The diminished ability of mammography to screen these women, however, does not seem to negatively affect women's breast cancer prognosis.
"What we know, without any question, is that performing mammograms on women with implants is more technically challenging in order to get optimum images," says Carol H. Lee, M.D., member of the American College of Radiology (ACR) Board of Chancellors and chair of the ACR's Breast Imaging Commission."It is more difficult because the presence of the implants usually does obscure some of the tissue. This is even true for implants that are behind the pectoralis muscle."
Another message that plastic surgeons should be sending breast augmentation patients is that women should notify mammography centers that they have implants before they go in for screening mammographies. The centers should know to schedule these patients for four, instead of two, views for each breast, according to Dr. Lee, who is an attending physician and professor of diagnostic radiology at Yale University School of Medicine, New Haven, Conn.
TECHNIQUE MATTERS Donita Shipman, R.T., (R)(M)(QM), a control technologist, Bothwell Regional Health Center, Sedalia, Mo., and American Society of Radiologic Technologists' mammography chapter steering committee chairperson, explains that, even with four views, technologists experienced in imaging women with breast implants will still miss from 20 percent to 25 percent of the tissue on the mammogram.
"That is because of the inability of the x-ray to penetrate the implant. You cannot see through or behind it. So it is very important for patients to seek out a facility that does a significant amount of screening of these type of patients. Experienced technologists are proficient in getting the appropriate breast tissue," Ms. Shipman says.
DATA POINTS Dr. Lee says a study in the Journal of the American Medical Association (Miglioretti et al 2004) helps to quell confusion on the issue.
The authors compared the accuracy of screening mammography and tumor characteristics in women with and without implants from January 1, 1995, to October 15, 2002. They found that the sensitivity of mammography was 45 percent in women with implants versus 67 percent in women without implants. They reported that, while breast augmentation decreases the sensitivity of screening mammography among asymptomatic women, it does not increase the false-positive rate. Additionally, the decreased sensitivity did not influence the prognostic characteristics of tumors, according to the study.
Dr. Lee says that there is no significant difference between the imaging quality of silicone gel and saline implants.
"Both will obscure tissue," she says.
Nor does implant placement make that much of a difference when it comes to mammography.
"More and more surgeons are putting the implants behind the muscle, and I have had patients tell me that their plastic surgeons have told them that, because it was behind the muscle it does not obscure breast tissue. That is not necessarily true," Dr. Lee says.
Walter Erhardt, M.D., American Society of Plastic Surgeons (ASPS) past president and the chair of the ASPS Public Education Committee, agrees and says it is not so much where the implant is placed, but rather, how much scar tissue forms around it that can affect mammography.
CAPSULAR CONTRACTURE PROBLEMATIC Dr. Erhardt, who practices in Albany, Ga., says he believes that the biggest factor hindering the clear determination of lumps in the breast by manual or radiologic examination is capsular contracture.
"With capsular contracture, it is harder to do the displacement view for the mammogram," Dr. Erhardt explains.
Ms. Shipman agrees that capsular contracture presents the biggest problem for technologists.