Stereotactic Core Biopsy Following Screening Mammography: A Danish Retrospective National Cohort Study

Background: Since introducing stereotactic core biopsy (SCB) on breast lesions in Denmark, no national follow-up of the procedure has been executed. Purpose: To evaluate performance of SCB in Danish mammography screening. 3 areas were selected for evaluation: diagnostic value of SCB, performance of the Danish 7-tier mamma-radiological classifications system, DKBI-RADS, and diagnostic delay for SCB-diagnosis. Materials & Methods: Danish retrospective national cohort study including 2195 screening patients undergoing SCB. Study period: 01.01.2010 to 30.09.2012. Patients were identified from The Danish National Patient Register. Pathology-data were obtained from the Danish Pathology Database. Radiological-data according to DKBI-RADS were recorded. Diagnostic delay from clinical mammography until diagnosis was registered. Results: 173 SCBs indicated cancer; all operated with 3 cases finalized as benign. 1296 cases were determined benign with diagnostic surgery in 81 cases of which 31 were concluded pre-malignant/malignant. Correlation between DKBI-RADS and pathology diagnosis: 329 of 485 DKBI-RADS3, 227 of 450 DKBI-RADS4 were benign. 4 of 16 DKBI-RADS5 were benign. The diagnostic value of pre-malignant/malignant SCB related to results from surgery showed 94.4% sensitivity and a positive predictive value of 93.9%. Median diagnostic-time of single-biopsy was 13 days. Conclusion: The performance of SCB in Denmark is comparable to international studies regarding the diagnostic value of malignant SCB. The study indicates that DKBI-RADS classifications are not used consistently regarding micro-calcifications selected in screening-mammographies. Diagnostic delay is acceptable, subject to EUSOMA specifications, regarding single-biopsy.