MRI, mammography better than mammography alone for high-risk patients
Screening with both MRI and mammography might rule out cancerous lesions better than mammography alone in women who are known or likely to have an inherited predisposition to breast cancer, according to a systematic review published in the May 6 issue of the Annals of Internal Medicine.

Ellen Warner, MD, and colleagues from Sunnybrook Health Sciences Center, Odette Cancer Center and Cancer Care Ontario in Toronto, undertook the study to summarize the sensitivity, specificity, likelihood ratios and posttest probability associated with adding MRI to annual mammography screening of women at very high risk for breast cancer.

The researchers reviewed the MEDLINE, EMBASE and Cochrane databases from January 1995 to September 2007, supplemented by hand searches of pertinent articles.

Two reviewers assessed studies, and data were extracted and entered into 2 x 2 tables that compared American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) scores of MRI plus mammography, mammography alone, or MRI alone with results of breast tissue biopsies.

The investigators identified 11 relevant, prospective, nonrandomized studies that ranged from small single-center studies with only one round of patient screening to large multicenter studies with repeated rounds of annual screening. Characteristics of women that varied across study samples included age range, history of breast cancer and BRCA1 or BRCA2 mutation status.

Based on their review, Warner and colleagues found the summary negative likelihood ratio and the probability of a BI-RADS–suspicious lesion (given negative test findings and assuming a 2 percent pretest probability of disease) were 0.70 and 1.4 percent for mammography alone and 0.14 and 0.3 percent for the combination of MRI plus mammography, using a BI-RADS score of 4 or higher as the definition of positive.

The researchers noted that the limitations included: differences in patient population, center experience and criteria for positive screening results led to between-study heterogeneity. For example, criteria for suspicious lesions varied across studies.

As a result of their review, the authors wrote that “screening women at very high risk for breast cancer, with both MRI and mammography, might rule out cancerous lesions better than mammography alone.”