Screening for breast cancer with MRI: recent experience from the Australian Capital Territory

The American Cancer Society now recommends annual MRI screening for women at 20-25% or greater lifetime risk of breast cancer. The role of MRI screening in other risk subgroups is unproved because of insufficient data. Our study comprised 209 breast MRI scans carried out in 171 asymptomatic patients (age range 22-67 years, mean 46 years), referred between January 2005 and June 2008. Targeted ultrasound was carried out in 32 episodes (15%) and biopsies were taken in 23 patients (13%). In four patients, MR-guided procedures were required to establish a diagnosis, two using hook-wire localization and two by means of vacuum-assisted biopsy. Seven cancers were detected by MRI in the 171 patients, with a yield of 4.1%. Only one of the seven cancers was also shown by x-ray mammography. Four patients had invasive ductal cancer (all axillary node negative) and three had high-grade ductal carcinoma in situ or pleomorphic lobular carcinoma in situ. The three women with in situ disease were all potentially high risk, based on the National Breast and Ovarian Cancer Centre (NBOCC) criteria. Three women with invasive breast cancer were at only average risk based on NBOCC criteria, but two of these had extremely dense breasts. A fourth patient, found to have multifocal invasive cancer, had a personal history of contralateral breast cancer, but no relevant family history. Our findings suggest that breast MRI could be used to screen a larger Australian population at increased risk of developing breast cancer.