April 4, 2012
CHARLESTON -- Women at high-risk for developing invasive breast cancer now have a more definitive answer for appropriate screening methods, thanks to the reported results of an American College of Radiology Imaging Network (ACRIN) trial reported April 4 in the Journal of American Medical Association. The study confirms a significant breast cancer detection benefit by supplementing annual mammography screening with ultrasound in women at elevated risk due to dense breast tissue and at least one additional risk factor such as a personal and/or family history of the disease. The study also found that that a single screening MRI following three years of annual mammography and ultrasound screenings identified additional cancers. The vast majority of additional cancers detected by the supplemental ultrasound and MRI screenings were early-stage invasive cancers that had not spread to the lymph nodes.
"For women who have dense breasts, adding ultrasound to mammography will increase the chance of finding invasive cancer before it spreads to lymph nodes," said the trial's principal investigator Wendie Berg, M.D., Ph.D., professor of radiology at the University of Pittsburgh School of Medicine, Magee-Womens Hospital of UPMC. "MRI detected additional invasive cancers not seen on mammography or ultrasound; however, we found that MRI was significantly less tolerable than mammography or ultrasound for many study participants. Of participants offered an MRI, only 58 percent accepted the invitation."
Berg also noted that the study results confirm that mammography alone is not the best screening process for women with dense breasts. MUSC College of Medicine Dean Etta Pisano, M.D., served as a co-author and investigator of the study, and agreed with Berg that study results illuminated a much better picture of what ultrasound screening can do to protect high-risk women, and that a costly MRI is not always the answer.
"It is important for each patient to speak with her physician about which screening process is most appropriate given her own medical history" said Pisano. "Women with dense breast tissue should not assume that having an ultrasound or MRI is essential."
Study results were reported for 2,662 women at increased breast cancer risk who had three annual mammography plus ultrasound screenings and for a subset of 612 study participants who agreed to undergo an MRI after completing all three mammography and supplemental ultrasound screenings. A total of 111 breast cancer diagnoses were made in 110 study participants with 33 (30 percent) cancers seen only by mammography and 32 (29 percent) cancers seen only by the supplemental ultrasound, for an added annual cancer detection rate due to ultrasound of 4.3 cancers per 1,000 screens. The single MRI screening revealed additional cancers not seen by mammography or ultrasound at a rate of 14.7 per 1,000 screens. Nine (8 percent) cancers ("interval" cancers) were detected clinically in between the annual imaging exams (1.2 per 1,000 screens).
Of the 32 cancers seen only on ultrasound, 30 (94 percent) were invasive, accounting for a 34 percent absolute increase in invasive cancer detection, and of the nine cancers seen only on MRI, eight (89 percent) were invasive.
"While supplemental ultrasound and MRI screening detect more cancers, it is important to emphasize that an annual mammogram is still recommended and neither ultrasound nor MRI is meant to replace mammography," said Ellen Mendelson, M.D., co-investigator and Lee F. Rogers Professor of Radiology at the Feinberg School of Medicine, Northwestern University, Chicago. "Further, women who have a screening MRI do not need screening ultrasound," Berg added.
The authors also reported the risk of false positives decreased significantly with annual screening ultrasound (years two and three) in this study compared with the first screen. "However, the rates of biopsy and false-positive exams were still substantial: in years two and three combined, supplemental ultrasound increased the recall rate by 7 percent and biopsy rate by 5 percent with only 7 percent of additional biopsies showing cancer. The single supplemental MRI screen increased the recall rate by 20 perent and biopsy rate by 7 percent with 19 percent of biopsies prompted only by MRI showing cancer," noted Zheng Zhang, Ph.D., protocol statistician with the ACRIN Biostatistics Center and assistant professor in the Department of Biostatistics at Brown University in Providence, R. I.
The study was made possible through funding from a novel private-public partnership between the Avon Foundation and the National Cancer Institute (NCI), part of the National Institutes of Health (NIH).
ACRIN is a clinical trials research organization and member of the National Cancer Institute's Cooperative Group Program. With investigators from over 100 academic and community-based facilities in the United States and abroad, ACRIN's multicenter research encompasses oncologic and cardiac imaging science. ACRIN's oncology mission is to disseminate information that increases the length and quality of life of cancer patients. ACRIN and the Eastern Cooperative Oncology Group are merging their oncologic research programs to conduct clinical trials as the ECOG-ACRIN Cancer Research Group. The overarching goal of its cardiovascular research is to determine the appropriate use of diagnostic CV imaging tests. ACRIN is administered by the American College of Radiology and is headquartered at the ACR Clinical Research Center in Philadelphia, PA. The ACRIN Biostatistics Center is located at Brown University in Providence, RI.
Founded in 1824 in Charleston, The Medical University of South Carolina is the oldest medical school in the South. Today, MUSC continues the tradition of excellence in education, research, and patient care. MUSC educates and trains more than 3,000 students and residents, and has nearly 13,000 employees, including approximately 1,500 faculty members. As the largest non-federal employer in Charleston, the university and its affiliates have collective annual budgets in excess of $1.7 billion. MUSC operates a 700-bed medical center, which includes a nationally recognized Children's Hospital, the Ashley River Tower (cardiovascular, digestive disease, and surgical oncology), and a leading Institute of Psychiatry. For more information on academic information or clinical services, visit www.musc.edu. For more information on hospital patient services, visit www.muschealth.com.