According to the results of a study presented at the 2008 annual meeting of the American Society of Clinical Oncology (ASCO), the number of mastectomies performed for early-stage breast cancer at the Mayo Clinic increased by 13% over a three-year period.¹ Increasing use of preoperative magnetic resonance imaging (MRI) may explain some of the increase in mastectomy rates.

In 1990, the National Institutes of Health issued a statement that for most women with Stage I or Stage II breast cancer, breast-conserving therapy (lumpectomy plus radiation therapy) is as effective as mastectomy with respect to overall survival. Since that time breast-conserving therapy has become a standard treatment option for early-stage breast cancer.

A recent study from Brazil has reported that MRI examinations increased mastectomies by 27% in 99 patients treated for breast cancer in 2004-2005.² These authors attributed this observation to a more accurate determination of local extent of cancer spread by the use of MRI.

Recently, however, researchers at the Mayo Clinic noted an increase in the use of mastectomy for early-stage breast cancer. To evaluate patterns in the use of mastectomy, the researchers conducted a retrospective study of 5,464 women who had surgery for early-stage breast cancer between 1997 and 2006.

• Mastectomy rates declined from 45% in 1997 to 30% in 2003, but then increased to 43% in 2006.
• Rates of preoperative MRI increased from 11% in 2003 to 22% in 2006.
• 52% of women who had preoperative MRI chose a mastectomy, compared with 38% of women who did not have preoperative MRI.
• Although mastectomy rates were lower in women who did not have preoperative MRI, mastectomy rates also increased in these women between 2003 and 2006.

Comments: This study suggests that preoperative breast MRI may contribute to increased use of mastectomy among women with early-stage breast cancer. Other factors may also be contributing to use of mastectomy, however, such as improvements in breast reconstruction and increasing use of genetic testing.

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Reference: 

¹ Katipamula R, Hoskin TL, Boughey JC et al. Trends in mastectomy rates at the Mayo Clinic Rochester: Effect of surgical year and pre-operative MRI. Proceedings from the 44th annual meeting of the American Society of Clinical Oncology. Chicago, IL. 2008. Abstract #509.

² Mameri CSm Kemp C, Goldman SM, et al. Breast Journal. 2008;14:236-234.