Screening MRI Does Not Increase Cancer Detection or Result in an Earlier Stage at Diagnosis for Patients with High-Risk Breast Lesions: A Propensity Score Analysis.

Abstract

Guidelines recommend consideration of screening MRI for patients with high-risk breast lesions (HRLs), acknowledging limited data for this moderate-risk population. This study identified patients with atypical ductal/lobular hyperplasia (ADH/ALH), lobular carcinoma in situ, (LCIS) or both evaluated at our high-risk clinic. Patients were categorized as having received screening mammography (MMG) alone vs. MMG and breast MRI (MMG+MRI). Inverse probability weighting based on propensity scores (PS) representing likelihood of MRI use was applied to Kaplan-Meier and Cox regression analyses to determine cancer detection and biopsy rates by screening group. Among 908 eligible patients, 699 (77%) patients with available follow-up data were analyzed (542 with ADH/ALH and 157 with LCIS). Of the 699 patients, 540 (77%) received MMG alone, and 159 (23%) received MMG + MRI. The median follow-up period was 25 months, during which a median of two MRIs were performed. After PS-weighting, the characteristics of each screening group were well-balanced with respect to age, race, body mass index (BMI), menopausal status, breast density, family history, HRL type, and chemoprevention use. The 4year breast cancer detection rate was 3.6% with both MMG alone and MMG+MRI (p = 0.89). The breast biopsy rates were significantly higher with MMG+MRI (30.5% vs12.6%; hazard ratio [HR], 2.67; p < 0.001). All breast cancers were clinically node-negative and pathologic stage 0 or 1. Among five cancers in the MMG+MRI group, two were MRI-detected, two were MMG-detected, and one was detected on clinical exam. Screening MRI did not improve cancer detection, and cancer characteristics were favorable whether screened with MMG alone or MMG + MRI. These findings question the benefit of MRI for patients with HRL, although longer-term follow-up study is needed.