However, other large multicenter studies, such as the comparative effectiveness of MRI in breast cancer (COMICE) trial, showed the addition of MRI to conventional imaging was not significantly associated with a reduced reoperation rate, with 153 (19%) needing reoperation in the MRI group versus 156 (19%) in the non-MRI group (odds ratio [OR], 0.96; 95% CI, 0.75-1.24; P = . 77) [70]. Although the findings are important, limitations from the COMICE trial are also noted, such as its inclusion of patients from several small centers where technical factors and varying degree of experience among interpreting radiologists could have influenced the MRI results. It is also not clear that the data from the MRI was incorporated into surgical planning, and nearly 7% of the group assigned to MRI did not actually have an MR interpreted (analyzed by intention to treat). When all breast cancer subtypes were included, a meta-analysis of 19 studies did not find evidence that MRI impacted the rates of re-excision, reoperation, or positive margins, but MRI was significantly associated with increased odds of receiving contralateral prophylactic mastectomy (OR, 1.91; 95% CI, 1.25-2.91; P = . 003) [71]. This analysis of 85,975 women also showed that preoperative MRI was associated with increased odds of receiving mastectomy (OR, 1.39; 95% CI, 1.23-1.57; P < . 001) [71]. Still, it is unknown whether some of the studies included in that meta-analysis had a bias in randomization (ie, women who were preplanned for mastectomies were more likely to have been referred rather than randomized to the preoperative MRI arm). As an example of this, in the multicenter international prospective analysis cited above [69], mastectomy was already planned based on conventional imaging in 22.4% (MRI group) versus 14.4% (no MRI group) (P < . 001). The data are different for ILC histological subtypes. For ILC, there is strong evidence that MRI improves surgical outcomes [72-81].
Imaging of Invasive Breast Cancer. However, other large multicenter studies, such as the comparative effectiveness of MRI in breast cancer (COMICE) trial, showed the addition of MRI to conventional imaging was not significantly associated with a reduced reoperation rate, with 153 (19%) needing reoperation in the MRI group versus 156 (19%) in the non-MRI group (odds ratio [OR], 0.96; 95% CI, 0.75-1.24; P = . 77) [70]. Although the findings are important, limitations from the COMICE trial are also noted, such as its inclusion of patients from several small centers where technical factors and varying degree of experience among interpreting radiologists could have influenced the MRI results. It is also not clear that the data from the MRI was incorporated into surgical planning, and nearly 7% of the group assigned to MRI did not actually have an MR interpreted (analyzed by intention to treat). When all breast cancer subtypes were included, a meta-analysis of 19 studies did not find evidence that MRI impacted the rates of re-excision, reoperation, or positive margins, but MRI was significantly associated with increased odds of receiving contralateral prophylactic mastectomy (OR, 1.91; 95% CI, 1.25-2.91; P = . 003) [71]. This analysis of 85,975 women also showed that preoperative MRI was associated with increased odds of receiving mastectomy (OR, 1.39; 95% CI, 1.23-1.57; P < . 001) [71]. Still, it is unknown whether some of the studies included in that meta-analysis had a bias in randomization (ie, women who were preplanned for mastectomies were more likely to have been referred rather than randomized to the preoperative MRI arm). As an example of this, in the multicenter international prospective analysis cited above [69], mastectomy was already planned based on conventional imaging in 22.4% (MRI group) versus 14.4% (no MRI group) (P < . 001). The data are different for ILC histological subtypes. For ILC, there is strong evidence that MRI improves surgical outcomes [72-81].