PERFORMANCE OF FINE-NEEDLE ASPIRATION CYTOLOGY OF THE BREAST-MULTICENTER STUDY OF 23,063 ASPIRATES IN 10 ITALIAN LABORATORIES

Aims and Background: The aim of this study was to assess the performan ce of routine breast cytology in a group of Italian laboratories, as a basis for interlaboratory quality control. Methods: A multicenter ret rospective consecutive series of 23,063 aspirates from breast lesions (5,130 invasive carcinoma, 247 intraductal carcinoma, 2,386 benign les ions [histological], 13,144 benign lesions [follow-up], 2,156 other [n o follow-up]) was reviewed. Standard accuracy measurements (inadequacy rate, sensitivity, specificity, predictive value) were determined, as well as the contribution of diagnostic tests such as physical examina tion and instrumental diagnostic procedures (mammography, sonography). Results: Overall, inadequacy rate was 6.5% for malignant and 23.2% fo r benign lesions. Sensitivity was 92.2%, specificity was 95.3%, and th e positive predictive value of an equivocal or malignant report was 53 .4% or 96.9%, respectively. Sensitivity was associated with histologic al type (intraductal vs invasive: 77.0% vs 92.9%, p<0.000001; lobular vs other invasive: 85.5% vs 94%, p = 0.0025) as well as with tumor siz e (pT1 = 91.6%, pT2 = 94.3%, pT3-4 = 96.0%, p<0.000001). Observed diff erences in performance indicators between centers may be explained by variability in sampling or reading accuracy, and warrant the need for some adjustment in single centers, especially, as far as the criteria to report an equivocal smear are concerned. Cytology contributed to de tect otherwise unsuspected carcinomas, although in some centers this b enefit was poor and not cost-effective because a large number of unnec essary biopsies were caused by false equivocal/positive reports. Concl usions: Although centers scored, on average, well within standards rec ommended by national authorities, this study suggests the opportunity of interlaboratory quality control to achieve more homogeneous criteri a.