Adjunctive imprint cytology of core needle biopsy specimens improved diagnostic accuracy for breast cancer

Objective: Recently, therapies targeting the biological characteristics of individual cancers according to markers indicating underlying molecular biological mechanisms have become available. Core needle biopsy (CNB) is widely used, not only to diagnose, but also to determine therapeutic strategies, in patients with breast cancer. Although the diagnostic accuracy of CNB is acceptably high, false-negative results have occasionally been encountered. Methods: The results of adjunctive imprint cytology (AIC) coinciding with CNB in 2,820 patients suspected to have breast cancer were retrospectively reviewed. The feasibility and clinical usefulness of AIC-assisted diagnosis were analyzed. Results: Fourteen-hundred and sixty-four cases were diagnosed as not malignant using CNB alone. Forty-seven of 1464 cases were suspected to be malignant on a cytological review of AIC, and 42 were confirmed to be breast cancer on additional biopsies. The combination of CNB and AIC achieved a sensitivity of 100% (1398/1398) and a specificity of 99.6% (1417/1422). Small lesions and large noninvasive- or scirrhous-type carcinomas were the common features of the CNB-negative/AIC-positive cases. Conclusions: Adjunctive imprint cytodiagnosis is a simple and easy procedure that assists the pathological diagnosis of breast cancer using CNB and therefore serves as a possible novel standard application.