IMMUNOCYTOCHEMICAL STAINING OF PS2-PROTEIN IN FINE-NEEDLE ASPIRATE FROM BREAST-CANCER IS AN ACCURATE GUIDE TO RESPONSE TO TAMOXIFEN IN PATIENTS AGED OVER 70 YEARS

Fine-needle aspirates from 52 breast cancers in 50 patients over 70 years of age were immunocytochemically stained for pS2 protein. All patients were treated with tamoxifen 40 mg/day and followed up at intervals of 2 months. The size of the tumour was serially assessed with calipers and portable ultrasonography. Change in tumour size was confirmed mammographically. Clinical monitoring was performed blind of the pS2 status. Twenty-five tumours were pS2 positive; of which 23 showed a significant response; ten went into complete remission (mean time to complete remission 6.8 (range 2-14) months) and 13 demonstrated partial remission (mean follow-up 8.9 (range 6-19) months). Two tumours remained static. Twenty-seven tumours were pS2 negative and none of these responded to tamoxifen; six remained static (mean follow-up 11.5 (range 6-14) months) and 21 progressed (mean time to progression 7.0 (range 3-14) months) (P<0.001). Immunocytochemical assessment of fine-needle aspirates from elderly women with breast cancer accurately predicts a worthwhile response to tamoxifen.