Objective: The purpose of this study is to determine the patient compliance with and diagnostic yield of 18-month unilateral mammography in surveillance of probably benign (BI-RADS category 3) lesions.
Materials and methods: This retrospective study identified lesions prospectively classified BI-RADS 3 in asymptomatic women from January 1, 2004, to December 31, 2008. Surveillance protocol for BI-RADS 3 lesions included 6-month (unilateral), 12-month (bilateral), 18-month (unilateral), and 24-month (bilateral) imaging, with subsequent annual screening. Demographics, surveillance data, BI-RADS upgrades and downgrades, and biopsy results were abstracted from the longitudinal medical record.
Results: One thousand one hundred eighty-eight lesions in 1077 patients (mean age, 51.5 years; age range, 26-89 years) had BI-RADS 3 assessment, representing 1.07% of all screening examinations. The compliance rates for follow-up at 6, 12, 18, and 24 months were 83.3%, 75.9%, 54.8%, and 53.9%, respectively. Sixty lesions were upgraded to BI-RADS 4 or 5 during surveillance. Biopsy revealed 15 cancers (cancer yield of 1.47%) from 1017 lesions with either 24-month imaging stability or tissue diagnosis available. Five, six, one, and three cancers were detected at 6, 12, 18, and 24 months, respectively. Cancers were all stage 0 or 1 except for one stage 2A cancer. Seven hundred forty-four of 1188 (62.6%) BI-RADS 3 lesions were downgraded before completing 2-year surveillance.
Conclusion: Most (11/15 [73%]) breast cancers initially assessed as BI-RADS 3 are diagnosed at up to 12 months' surveillance. Eighteen-month unilateral mammography performed as BI-RADS 3 surveillance contributes minimally to cancer detection and has poor patient compliance.