A novel diagnostic index for use in the breast clinic.

The diagnostic accuracy of clinical examination, mammography, ultrasonography and fine needle aspiration (FNA) cytology in discriminating between benign and malignant breast lesions has been retrospectively assessed in 603 patients who attended the Professorial Breast Clinic and then underwent surgical biopsy, in Aberdeen Royal Infirmary, between January 1989 and September 1992. In this series of patients, FNA cytology gave the highest overall prediction of malignancy (92.6%) with a sensitivity of 87% and a specificity of 98%, whilst ultrasonography gave the lowest correct overall prediction (75.6%), with a sensitivity of 70% and a specificity of 79%. Using all the available findings (clinical examination, mammography, ultrasonography, FNA) as well as the patients' age, a stepwise logistic discriminant analysis was used to derive a mathematical equation for use as a novel diagnostic index. Weighted scores, derived from each variable, were used in the discriminant equation to predict the likelihood of malignancy in patients of different ages (>90%). For young patients (<35 years) the discriminant analysis predicted the diagnosis in 98% of women correctly. Quadruple assessment provides an opportunity for establishing the likely diagnosis in most patients the same day they visit the Breast Clinic. The diagnostic index, currently being evaluated prospectively in our breast clinic, may be a further aid to establishing a correct diagnosis.