Fine needle aspiration cytology is a valuable adjunct to axillary ultrasound in the preoperative staging of breast cancer

Aims To compare the predictive values of axillary ultrasound (US) combined with fine needle aspiration (FNA) cytology with tumour size (T stage) and grade in the preoperative staging of breast cancer. More precise definition of axillary FNA reporting nomenclature is also presented. Patients and Methods 314 patients: 119 patients had suspicious US investigated by FNA, 195 patients had normal US not investigated further preoperatively. This study examined the node-positive and node-negative cases in these two groups, calculating predictive values for cytology, US, T stage and tumour grade, and tested comparisons for significance. Results Axillary FNA has a positive predictive value of 84.8% compared with US (66.7%). The difference is significant (p=0.008). Negative US has a negative predictive value of 81.0% compared with a negative predictive value for cytology of 66.7%, but the difference is not significant (p=0.08). 43% of patients with unsatisfactory cytology were node positive. Of 195 patients with negative axillary US, 37 (19%) had metastatic nodal disease. Fewer than 20% of these patients had micrometastases alone. Tumour size and grade influenced node status in US-suspicious cases only. Conclusion Axillary FNA adds significantly to the positive predictive value provided by US. US gives false-negative results in 19% of cases and only a small proportion of these can be explained by micrometastases. Unsatisfactory cytology needs to be repeated because of a high rate of positive nodes in this group.