CHICAGO—Mastectomy rates have been on the upswing at the Mayo Clinic in Rochester, Minnesota, and researchers cited MRI as a factor influencing the increase.
“Our study showed that a significant number of women with early-stage breast cancer are undergoing mastectomy, and it appears to be partially related to the introduction of preoperative MRI,” Rajini Katipamula, MD, senior clinical fellow in hematology/oncology, said at ASCO 2008 (abstract 509).
Preoperative MRI identifies an additional 11% to 31% of lesions in the ipsilateral breast and 3% in the contralateral breast, and changes the surgical management in up to one-quarter of cases. To date, there have been no longitudinal data on the association between MRI and mastectomy, according to Dr. Katipamula.
The Mayo study cohort had 5,405 women (5,583 cancers) with stage 0 (DCIS), I, or II breast cancer treated between 1997 and 2006.
In 1997, the mastectomy rate was 45%, but it dropped to 31% in 2003 after lumpectomy was shown to be effective. After 2003, the rate rose again to 43% in 2006, appearing to correspond with the rise in preoperative breast MRI, which also rose from 10% to 23% (see Figure below).
The 2006 mastectomy population included 41% of women with DCIS, 33% with stage I cancer, and 57% with stage II cancer.
Women who underwent preoperative MRI were significantly more likely to have mastectomies
|Does MRI increase mastectomy? |
— MARY BETH TERRY, PHD
|The Mayo MRI study adds to several lines of evidence suggesting that preoperative MRI may alter decisions and pick up additional tumors,” said Dr. Terry, associate professor of public health, Columbia University. “Preoperative MRI was associated with an increase in mastectomies, but we saw other aspects in the study. There was indeed a doubling in women getting preoperative MRI, but the absolute increase was just 3%. The absolute increase over time was greater, 12%, without preoperative MRI,” she pointed out. This might be accounted for by baseline differences in patients selected for MRI that may lead to physician and/or patient preference toward mastectomy, she suggested. While the longitudinal design is unique and the quality of the data is strong, this is a single-institution study that may be infl uenced by temporal fl uctuations and other concurrent treatments, she said. Further, these results may not have an impact on mortality. “We know that with small lesions, switching from breast-conserving surgery to mastectomy will lower recurrence, but has no impact on mortality,” she noted.|
than those who did not. In 2006, mastectomies were done on 51% of women with preoperative MRI (up from 48% in 2003) and in 41% of those without it (up from 29%), she reported.
Over the 4-year period, the average difference in mastectomy rates between patients who underwent MRI vs those who did not was 53% vs 36%, Dr. Katipamula said.
In a multivariate analysis, having preoperative breast MRI raised the odds of undergoing mastectomy by 60% (P = .003). Having surgery in 2006 vs 2003 raised the odds by 70% (P < .0001).
Possible reasons for the increase observed in patients without preoperative MRI include anxiety over having cancer, concern about a personal or family history, better options for reconstruction, and increased awareness of the role of genetics, Dr. Katipamula suggested.