Trends and clinical implications of preoperative breast MRI in Medicare beneficiaries with breast cancer.

While there has been increasing interest in the use of preoperative breast magnetic resonance imaging (MRI) for women with breast cancer, little is known about trends in MRI use, or the association of MRI with surgical approach among older women. Using the Surveillance, Epidemiology and End Results-Medicare database, we identified a cohort of women diagnosed with breast cancer from 2000 to 2009 who underwent surgery. We used Medicare claims to identify preoperative breast MRI and surgical approach. We evaluated temporal trends in MRI use according to age and type of surgery, and identified factors associated with MRI. We assessed the association between MRI and surgical approach: breast-conserving surgery (BCS) versus mastectomy, bilateral versus unilateral mastectomy, and use of contralateral prophylactic mastectomy. Among the 72,461 women in our cohort, 10.1 % underwent breast MRI. Preoperative MRI use increased from 0.8 % in 2000-2001 to 25.2 % in 2008-2009 (p < 0.001). Overall, 43.3 % received mastectomy and 56.7 % received BCS. After adjustment for clinical and demographic factors, MRI was associated with an increased likelihood of having a mastectomy compared to BCS (adjusted odds ratio = 1.21, 95 % CI 1.14-1.28). Among women who underwent mastectomy, MRI was significantly associated with an increased likelihood of having bilateral cancer diagnosed (9.7 %) and undergoing bilateral mastectomy (12.5 %) compared to women without MRI (3.7 and 4.1 %, respectively, p < 0.001 for both). In conclusion, the use of preoperative breast MRI has increased substantially among older women with breast cancer and is associated with an increased likelihood of being diagnosed with bilateral cancer, and more invasive surgery.