BREAST-CANCER IN WESTERN-AUSTRALIA IN 1989 .3. ACCURACY OF FNA CYTOLOGY IN DIAGNOSIS

A population-based study of all cases of breast cancer diagnosed in We stern Australia (WA) in 1989 revealed 701 cases of cancer in 692 women . Three hundred and ninety-six (56.5%) of these cancers had fine needl e aspiration (FNA) cytology. Forth-three cases were managed non-surgic ally, on the basis of an FNA diagnosis and without histologic follow u p. Of the cases with histological follow-up, 73% received an unequivoc al diagnosis of malignancy by FNA, and abnormal cells (atypical, suspi cious or malignant diagnoses) were reported in 94.2%. Of the cases, 3. 2% were reported as benign and in 2.6% the samples taken were unsatisf actory. There were no false positive cytological diagnoses of malignan cy. This study is the first to examine the results of FNA diagnosis of breast cancer from a medical community as a whole, rather than for in dividual or specialist units; the accuracy of diagnosis was similar fo r different pathology practices including public and private sector la boratories. Lower absolute sensitivity (the proportion of cases given an unequivocal diagnosis of malignancy) was seen in very small and ver y large tumours, pure duct carcinoma in situ (DCIS), and invasive lobu lar carcinoma. False negative rates (the proportion of cases given a b enign cytological diagnosis) were very low for all laboratories (0-4.5 %) and for all types of carcinoma, and the proportion of unsatisfactor y samples was exceptionally low for all laboratories (0-4.5%). The ove rall figures for accuracy are similar to those reported from other cen tres in Australasia and overseas, and confirm the effective use of FNA cytology throughout the clinical and pathology community in WA.