The use of preoperative Magnetic Resonance Imaging (MRI) in newly diagnosed breast cancer has been increasing. However, the value of MRI applied to the women with newly diagnosed breast cancer remains controversial. Therefore, this study focused on the association between preoperative MRI and surgical outcomes, which include mastectom y rate, breast conservation rate, and re-excision rate.

Material and methods:
A systematic literature search was performed by the Wan fang, VIP (Chinese biomedical databases), PubMed, Cochrane Library, Embase, and Vip databases. The keywords were "breast cancer", "magnetic resonance imaging", "mastectomy rate", "re-excision rate", and "breast conservation rate." A random-effects model was used to estimate the proportion of women with various outcomes in the MRI group, versus a non-MRI group. The odds ratio (OR) for each surgical outcome were calculated.

4 RCTs (Randomized Controlled Trial) met the eligibility criteria that included a total of 2312 patients with breast cancer. The analysis results of the MRI group versus the non-MRI group were as follows: Mastectomy rate of 15% versus 10%, OR 2.01, 95% CI 0.79-5.11, P=0.14; Breast conservation rate 84% versus 89%, OR 0.58, 95% CI 0.29-1.17, P=0.13; Re-excision rate 17% versus 19%, OR 0.76, 95% CI 0.37-1.54, P=0.45.

There was no significant association between preoperative MRI and surgical outcomes. This study suggested that the use of preoperative MRI should be selective. The results showed that the application of preoperative MRI didn’t improve the prognosis of breast cancer patients. More randomized trials are needed for further study due to limited randomized trials.