Statistical analysis of diagnostic failure of fine needle aspiration cytology (FNAC) in breast cancer

Fine-needle aspiration cytology (FNAC) was performed on 300 patients. Among those, 57 cases failed in accurate diagnosis of malignancy and 243 were successful. Fourteen clinicopathological factors altogether were analyzed to elucidate any correlation with FNAC failure using uni- and multivariate analysis. The univariate analysis in each clinicopathlogical factor showed that these error cases were vaguely palpable cancers, estrogen receptor (ER) positive cancers, small-sized of tumors, scattered type of cancer cell distribution in tumor tissues, with low tumor grade, with low Nottingham prognostic index (NPI), with benign-like ultrasound findings and with low TNM stage. The multivariate analysis revealed tumor grade was the strongest factor for all, followed by cellular distribution type of cancer cells and benign-like ultrasound findings. From these results, we speculated that diagnostic failure of FNAC at first clinic visit seemed to be caused by mainly two histocytological factors: extrinsic factor (structural factors of tissue-like tumor cells' distribution pattern, etc.); and intrinsic one (cellular factors of low atypism such as benign-like ultrasound finding, low tumor grade, and so on).