MRI may increase mastectomy for early-stage breast cancer

Preoperative magnetic resonance imaging may be a factor in the rising rate of mastectomy among women with early-stage breast cancer, a retrospective study suggests.

Investigators reviewed 5,596 stage 0-11 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 that 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 magnetic resonance imaging, one of the investigators noted in a preview of the findings presented during a press briefing at the annual meeting of the American Society of Clinical Oncology.

It was reported at the Mayo Clinic that 11% of the women who were studied in 2003 underwent preoperative breast MRI, but this had increased to 22% of women in 2006.

Patients who underwent preoperative breast MRI were significantly more likely to 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 rates in those patients increasing from 28% in 2003 to 41% in 2006.

After adjustment for age, stage, contralateral breast cancer, and density, pre-operative MRI was found to be an independent predictor of mastectomy (odds ratio 1.7, P less than .0001).

Surgical year was also found to be a predictor of mastectomy.

Compared with 2003, the odds ratios for mastectomy were 1.4 for 2004, 1.9 for 2005 and 1.7 for 2006 (P less than .0001).

It was noted that other factors might also play a role in the increasing number of women who are undergoing mastectomy.

It 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.

Chair of the ASCO Cancer Communications Committee and moderator of the press briefing, added that studies have shown that when breast MRI is performed at the time of early stage breast cancer diagnosis, more cancer is found in both the breast known to be affected and the contralateral breast than is found on mammography.

Doctor of the University of Washington and the Fried Hutchinson Cancer Research Center, both in Seattle said that it may be that these surgeries based on MRI are appropriate.

MRI referrals bias might also play a role in the increased mastectomy rates.

Additional study is required to further elucidate the influence of these various factors on surgical management, and to assess whether the changing trends in surgical management improve outcomes for women with breast cancer.