Impact of preoperative breast MRI on 10-year survival of patients included in the Swedish randomized multicentre POMB trial

Background: The value of preoperative breast MRI as an adjunct technique regarding its effect on re-excision rates has been a subject of discussion. No survival data regarding preoperative breast MRI are available from randomized studies. Methods: Ten-year follow-up of the POMB randomized multicentre study was analysed, evaluating MRI and its effect on disease-free survival (DFS) and overall survival (OS). Patients with newly diagnosed breast cancer were randomized to either preoperative MRI or conventional imaging. Kaplan-Meier plots were used to analyse DFS and OS, and Cox regression to estimate hazard ratios (HRs). Results: A total of 440 patients, aged 56 years or less, with newly diagnosed breast cancer were randomized to either preoperative MRI (220) or conventional imaging (220; control). Median follow-up for each group was 10 years. DFS rates were 85.5 and 80.0 per cent for the MRI and control groups respectively (P = 0.099). The risk of relapse or death was 46 per cent higher in the control group (HR 1.46, 95 per cent c.i. 0.93 to 2.29). OS rates after 10 years were 90.9 and 88.6 per cent in the MRI and control groups respectively (P = 0.427). The risk of death was 27 per cent higher in the control group (HR 1.27, 0.71 to 2.29). Locoregional, distant, and contralateral recurrence outcomes combined were increased in the control group (P = 0.048). A subgroup analysis of patients with breast cancer stages I-III showed that preoperative MRI improved DFS compared with conventional imaging, but this did not reach statistical significance (P = 0.057). Conclusion: After 10 years of follow-up, preoperative breast MRI as an adjunct to conventional imaging resulted in slightly, but nonsignificantly, improved DFS and OS.