Association of preoperative MRI with breast cancer treatment and survival: A single institution observational study

To evaluate the association between preoperative breast MRI with surgery type, contralateral cancer, recurrence-free (RFS) and overall survival (OS) in women with early-stage breast cancer.

In this dual-affiliated single institution, retrospective study, we identified women with Stage I-III breast cancer diagnosed between 03/01/2013-03/31/2016 with available follow-up. Patient and tumor characteristics were recorded. Two cohorts were created based on the use of preoperative MRI(PMRI) versus no preoperative MRI(no-MRI) with Wilcoxon signed-rank and χ2 tests utilized for cross-group comparisons. Kaplan-Meier, log-rank and cox proportional hazards model analysis were used to compare RFS and OS in women with and without MRI.

593 eligible patients were included [322(54.3 %) with PMRI, 271(45.7 %) no-MRI]. Mean patient age was younger (53.8 ± 11.8vs59.3 ± 12.6 years, p < 0.001) and dense breasts more common (51.6 %vs22.5 %, p < 0.001) in PMRI group. Seventeen bilateral cancers (5.3 %) were in PMRI [14/17(82.4 %) detected only on MRI] vs 10 (3.7 %) in no-MRI (p = 0.34). Molecular subtype distribution(luminal A:27.2 % vs 31.1 %; luminal B:51.8 %vs44.2 %; HER2:5.4 %vs4.2 %; triple negative:15.6 %vs20.5 %, p = 0.28) were similar in PMRI vs no-MRI groups. PMRI group had higher rates of cT2-4(45.0 %vs28.8 %, p < 0.001), cN+(27.3 % vs 18.1 %, p < 0.01), and neoadjuvant therapy (NAC, 41.3 % vs 18.8 %, p < 0.001). Total mastectomy(57.8 %vs51.3 %, p = 0.12), margin positivity(6.2 %vs7.4 %, p = 0.63), recurrence(10.2 %vs7.0 %, p = 0.20) and death rates(8.1 %vs7.7 %, p = 0.88) were similar in PMRI vs no-MRI. Mastectomy rates remained comparable after adjusting for age and breast density (p = 0.28). At median follow-up of 70 months(IQR, 64-70), time to recurrence was [PMRI:30(IQR, 19-47)vs no-MRI:23(IQR, 9-31) months, p = 0.04]. Contralateral cancers were identified sooner and more frequently in the no-MRI group [4(2.1 %)vs2(0.9 %) cancers, p = 0.32, 21 ± 20vs48 ± 13 months, p = 0.27]. There was no significant difference in 5-year RFS[hazard ratio(HR) 1.05, 95 %CI 0.67-1.67, p = 0.84] and OS[HR 0.94, 95 %CI: 0.51-1.74, p = 0.85] between PMRI and no-MRI groups even after adjusting for age, cancer type, breast density, cN stage, and NAC. which were different between two groups (RFS, HR 0.87, 95 %CI: 0.53-1.43, p = 0.57; OS, HR 0.78, 95 %CI: 0.40-1.52, p = 0.46). NHW patients had higher RFS compared to Black patients in PMRI group (HR 0.45, 95 % CI: 0.21-0.96, p = 0.04) in adjusted analysis.

Preoperative MRI utilization is not associated with improved surgical margin, 5-year RFS or OS in our cohort. This effect persisted after adjusting for patient age, tumor stage, cancer type, breast density and NAC. At post therapy surveillance, contralateral cancers are identified earlier and more frequently in the no-MRI group.