April 3, 2012— -- Here's one more study to add to the breast cancer screening debate: Annual mammogram screenings, combined with ultrasounds and MRIs, significantly increase the detection of cancer in women who had an elevated risk of breast cancer, new research has found.
Scientists at the University of Pittsburgh School of Medicine examined data from the American College of Radiology Imaging Network trial. Out of more than 2,600 women who were at increased risk of breast cancer (they either had dense breast tissue and at least one other risk factor, such as a family history of the disease), 53 percent of the cancers were detected through mammograms. Ultrasounds picked up 33 additional cases of breast cancer, and MRIs found nine more that were not detected by either ultrasounds or mammograms.
"For women with dense breasts who are at higher risk, cancers tend to be more advanced," said Dr. Wendie Berg, the trial's principal investigator and professor of radiology at the University of Pittsburgh School of Medicine. "The combination of ultrasound and mammography is quite effective in finding the cancers."
The research was published Tuesday in the Journal of the American Medical Association and funded by the Avon Foundation and the National Cancer Institute.
While women with dense breast tissue may be at higher risk of developing breast cancer, the conundrum is compounded by the fact that mammograms are less likely to detect the cancer, so researchers said this is where supplemental screening tools can help.
Of note from the study, although more cancers were detected (adding ultrasound led to 242 patients undergoing biopsies), only 7.4 percent of these women ended up having cancer.
Federal guidelines currently suggest that women older than 50 receive a mammogram once every two years. But those guidelines clash with recommendations from the American College of Obstetrics and Gynecology, and the American Cancer Society. Both organizations recommend women begin getting annual mammograms at age 40.
The new research comes on the heels of a Norwegian study published Sunday in the Archives of Internal Medicine that found that women who underwent regular mammogram screenings had an estimated 15 percent to 25 percent of breast cancers diagnosed, but raised the question as to whether the tumors might actually vanish without treatment.
Overdiagnosing and false-positives have long been part of the debate about breast cancer screenings, but Berg said most overdiagnosing occurs in women who have ductal carcinoma in situ, a cancer that hasn't spread past the milk ducts and is usually less severe than other forms of the disease.
"Oftentimes, DCIS will never come to matter in a woman's lifetime, but we didn't look at that," said Berg. "For these invasive cancers, it's hard to argue that they're not important because those are the ones more likely to spread and matter."
"The fundamental problem is that we have no evidence that detecting these cancers by ultrasound actually saves lives," said Dr. Daniel B. Kopans, a professor of radiology at Harvard Medical School. "With all the effort that has gone into ultrasound screening over the last decade, it is surprising that no one has done a randomized, controlled trial, which is the only way to know if finding these cancers actually saves lives."
The only screening tool that has been shown to reduce breast cancer death rates in the U.S. is mammograms. There has been a 30 percent decrease in deaths since 1990, Kopans said.
While Berg said that ultrasounds are cheaper and probably more readily available to more women, Kopans said "MRI has an even better chance of saving more lives.
"Ultrasound has shown important potential, but before the population is subjected to ultrasound screening, a randomized control trial should be done to prove its benefit," said Kopans.
Nevertheless, Berg believes there is a place for these supplemental screenings for women at higher risk of developing breast cancer.
"I don't have to be apologetic for overscreening when we found that 94 percent of the cancers found with these tools were invasive cancer, and 96 percent of them had not yet spread to lymph nodes," said Berg. "This is exactly the type of cancer that is appropriate for these screening tools."