Breast Cancer Screening Enters Era of Personalized Care
Studies indicating the high sensitivity of MR imaging for breast cancer screening, along with new screening guidelines prompted by those studies, are ushering in a new era of personalized care, according to some breast imagers.
 Mitchell D. Schnall, M.D., Ph.D. University of Pennsylvania |
National screening guidelines that endorsed annual MR imaging along with mammography for women at high risk of breast cancer constituted one of the top six cancer stories of 2007, according to an annual list released by the American Society of Clinical Oncology.
The new guidelines, issued by the American Cancer Society (ACS), came just two years after a large, multicenter trial indicated that digital mammography was more sensitive than film mammography in certain groups of women—generally those who were younger and had dense breasts.
Together the MR imaging and digital mammography findings, which could affect millions of women, mark the transition from a time when film mammography was the uniform screening modality to an era when choice of modality can depend on each woman's risk status. "Personalized approaches to breast cancer surveillance are here," said Mitchell D. Schnall, M.D., Ph.D., speaking in November at the annual cancer prevention meeting of the American Association for Cancer Research.
Infrastructure Must Evolve
The transition to personalized screening is far from complete, however. Clinicians translating the new guidelines into practice are dealing with practical and administrative issues. "We have not yet created a proper infrastructure," said Dr. Schnall, who heads the University of Pennsylvania’s radiology research division in Philadelphia. "Practical approaches to managing the personal surveillance system are going to be important for this to have a clinical impact."
For decades, breast cancer screening has been rooted in film mammography, with conversion to digital slowed by the need for high resolution. In 2005, however, the Digital Mammographic Imaging Screening Trial (DMIST) showed that digital mammography was more sensitive than film in women who were young, had dense breasts, were pre-menopausal or were going through menopause.
Use of digital mammography has since grown rapidly. According to the U.S. Food and Drug Administration, the proportion of certified mammography facilities with full-field digital units grew from about 6 percent in January 2005 to nearly 30 percent in January 2008.
The next step toward personalized screening came with successful MR imaging trials in women at high risk of breast cancer. The resulting ACS guidelines recommend annual MR imaging along with mammography for women who have a breast cancer (BRCA)1 or BRCA2 gene mutation; have a first-degree relative with a mutation; received radiation to the chest between ages 10 and 30 (usually as treatment for Hodgkin disease); have a lifetime risk of 20 percent or more as determined by an accepted risk assessment tool predominately based on family history; or have one of several rare syndromes that predispose women to breast cancer.
Other organizations are joining ACS in revising their screening guidelines. Until this year, the National Comprehensive Cancer Network (NCCN), a partnership of 18 large cancer centers across the country, had recommended that MR imaging be "considered" in conjunction with mammography for women who are at high risk because of a strong family history or genetic predisposition. In 2008, NCCN will strengthen the guideline for women who have a genetic predisposition to the disease, dropping the word "consider," said Therese Bevers, M.D., chair of NCCN's breast screening guidelines committee.
NCCN will continue to recommend that physicians consider screening with MR imaging for women with a strong family history. It is also adding a recommendation to consider MR imaging for those women with a history of lobular carcinoma in situ or thoracic radiation, said Dr. Bevers, who is medical director of the cancer prevention center at the M.D. Anderson Cancer Center in Houston.
Before ACS issued its guidelines, the anticipated growth rate for breast MR procedures was 40 percent a year through 2010, according to Nealie Hartman, clinical marketing manager in the MR division of Siemens Medical Solutions in Malvern, Pa. That rate has tripled since the guideline revision, making breast MR the fastest growing MR procedure, Hartman said.
Insurance Coverage, Follow-Up Issues Require Attention
As personalized screening becomes a reality, radiologists face practical issues. Insurance coverage of screening MR imaging can still be an obstacle even in the wake of the revised ACS guidelines, with radiologists interviewed for this article saying coverage is not automatic and can involve a good deal of peer-to-peer discussion with payors.
Also at issue is following up on positive MR imaging findings. ACS cautions women against getting MR imaging in a practice that does not also offer MR image-guided biopsy. However, smaller practices often do the MR imaging and then refer patients to a larger center for biopsy.
 Analog and digital mammograms of a moderately dense breast. |
Such a requirement creates a dilemma due to the variability in MR imaging protocols, said Jennifer Harvey, M.D., director of breast imaging at the University of Virginia in Charlottesville. Often the center doing the biopsy cannot readily use the referring center’s images. Practices may need to form a relationship with a center that does biopsies and set up their MR imaging breast screening protocols to match, said Dr. Harvey, who chairs the breast imaging subcommittee of the RSNA Scientific Program Committee. In addition, more practices may have to learn how to do MR image-guided biopsies, she said.
Perhaps the largest issue facing practices in a personalized screening era is how and when to determine a patient’s risk status. Prior to release of the new guidelines, most MR imaging breast cancer screening was among women with a strong family history and/or a genetic predisposition. New recommendations for MR imaging in women with a 20 percent or higher risk, however, cover a much broader group. ACS has estimated that its new guidelines could affect 1.4 million women.
The broader criteria suggest the need for a system to determine risk routinely in all women, said Dr. Schnall. This is already done in some academic centers like Penn’s risk clinic and at M.D. Anderson, where the radiology department works in conjunction with Dr. Bevers' cancer prevention clinic next door.
Most women who go for yearly mammograms, however, do not undergo a thorough risk evaluation. "If a woman today is very savvy about breast cancer risk, she likely will find a place for risk evaluation," Dr. Schnall said. "For the average busy woman, it's not clear anybody will steer her in the right direction."
"Clearly this is an evolving area and radiologists are likely to have a more important role in identifying women who are at high risk," said Dr. Harvey, noting that primary care physicians and gynecologists will likely join radiologists in the task.