Study Shows Annual MRI Plus Mammography May Be Effective Screening Program for Women at High Risk for Breast Cancer
The Ontario Breast Screening Program expanded in July 2011 to include screening of high-risk women aged 30 to 69 years with annual magnetic resonance imaging (MRI) and digital mammography. As reported by Chiarelli et al in Journal of Clinical Oncology, a study of the initial screen in the program indicated that annual MRI plus mammography can be successfully implemented in screening programs for high-risk women. Combined screening and MRI alone detected more cancers than mammography alone, combined screening had the highest positive predictive value, and the cancer detection rate was highest among women who were known risk mutation carriers.
Study Details
The study involved 2,150 women with initial screening examinations who underwent both mammography and MRI and had a final diagnosis. Women were eligible on the basis of high risk according to the following criteria: known mutation in BRCA1, BRCA2, or another gene predisposing to increased risk of breast cancer; untested first-degree relative of a gene mutation carrier; family history consistent with hereditary breast cancer syndrome and estimated lifetime breast cancer risk ≥ 25%; and radiation therapy to the chest before age 30 years and ≥ 8 years prior to the study.
Overall, 1,506 patients were aged < 50 years. The majority of women (91%) were screened with MRI within 30 days of mammography. Radiologists were aware of mammogram results before interpreting MRIs.
Screen Findings
Overall, 554 women (25.8%) had an abnormal screen result, 197 (9.2%) had a biopsy, and cancer was detected in 35 (1.6%). Of patients with abnormal exams, 133 had abnormal mammogram alone, 324 had abnormal MRI alone, and 97 had abnormal mammogram and MRI. Biopsy was performed on the basis of mammogram alone in 15 patients, MRI alone in 136, and both in 46.
Recalls were significantly more frequent on the basis of abnormal MRI alone (15.1%, P < .001) compared with abnormal mammogram and MRI (4.7%) or abnormal mammogram alone (6.4%). Recall was significantly less common on the basis of abnormal mammogram and MRI vs abnormal mammogram alone (P = .02).
Cancer Detection
Of the total of 35 breast cancers, none were detected by mammogram alone, 23 were detected by MRI alone (10.7 per 1,000 screening exams), and 12 were detected by both (5.8/1,000; P < .001 for both vs mammogram alone). Positive predictive value among women with an abnormal screening result was 7.1% for abnormal MRI alone and 12.4% for abnormal mammogram and MRI (P < .03 for both vs abnormal mammogram alone); positive predictive value among patients undergoing biopsy was 16.9% with abnormal MRI alone and 26.1% with abnormal MRI and mammogram.
The cancer detection rate was significantly higher among women with invasive cancer vs ductal carcinoma in situ (12.6 vs 3.7/1,000, P < .001) and among those who were known gene mutation carriers vs those with a family history and an estimated lifetime cancer risk of ≥ 25% (30.8 vs 6.9/1,000, P < .001) and nonsignificantly higher in women aged ≥ 50 years vs < 50 years (23.3 vs 13.3/1,000).
The investigators concluded, “Screening with annual MRI combined with mammography has the potential to be effectively implemented into an organized breast screening program for women at high risk for breast cancer. This could be considered an important management option for known BRCA gene mutation carriers.”
Anna M. Chiarelli, PhD, of Cancer Care Ontario, is the corresponding author for the Journal of Clinical Oncology article.
The authors indicated no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
