Preoperative magnetic resonance imaging may be a factor in the rising rate of mastectomy in women with early-stage breast cancer, a study suggests.
Investigators reviewed 5,596 stage 0-II breast cancers in 5,463 women who underwent surgery for the malignancy between 1997 and 2006 at the Mayo Clinic in Rochester, Minn. They found mastectomy rates decreased from 45% in 1997 to 30% in 2003, but then increased to 43% in 2006.
The rebound occurred in tandem with a doubling in the percentage of women who underwent preoperative breast MRI, investigator Matthew Goetz noted in a preview of the findings during a press briefing conducted by the American Society of Clinical Oncology (ASCO).
The study at ASCO's annual meeting. Its abstract was among thousands posted on the society's Web site in advance of the meeting. Under a new ASCO policy, only plenary and late-breaking abstracts have yet to be posted.
Dr. Goetz and his colleagues at the Mayo Clinic reported that 11% of women studied in 2003 underwent preoperative breast MRI, compared with 22% in 2006.
Patients who underwent preoperative breast MRI were significantly more likely to undergo mastectomy than were those who did not undergo preoperative breast MRI (52% vs. 38%). A similar increase in mastectomy rates was seen, however, in those who did not undergo preoperative MRI, with those rates increasing from 28% in 2003 to 41% in 2006.
After adjustment for age, stage, contralateral breast cancer, and density, preoperative MRI was found to be an independent predictor of mastectomy (odds ratio 1.7). Surgical year was also found to be a predictor of mastectomy: Odds ratios vs. 2003 for mastectomy were 1.4 for 2004, 1.9 for 2005, and 1.7 for 2006.
Dr. Goetz noted that other factors might also play a role in the increasing number of women undergoing mastectomy. He cited patient preference—some women choose mastectomy over lumpectomy to maximize their risk reduction—and changes in medical procedures and technologies, such as improved breast reconstruction options and the introduction of genetic testing.
Dr. Julie Gralow, chair of the ASCO Cancer Communications Committee and moderator of the press briefing, said studies have shown that when breast MRI is performed at the time of early-stage breast cancer diagnosis, more cancer is found in the breast known to be affected and in the contralateral breast than is found on mammography. “These surgeries based on MRI [may be] appropriate.”
MRI referral bias might also play a role in the increased mastectomy rates, said Dr. Gralow of the University of Washington and the Fred Hutchinson Cancer Research Center, both in Seattle.
MRIreferral bias may also play a role in the increased mastectomyrates. DR. GRALOW