DETECTION OF NUMERICAL CHROMOSOME-17 ABNORMALITIES IN FINE-NEEDLE ASPIRATES OF BREAST-CANCER USING A NOVEL IN-SITU HYBRIDIZATION SIGNAL AMPLIFICATION METHOD

We describe a method of in situ hybridization (ISH) to assess numerica l chromosome abnormalities on alcohol-fixed smears obtained by fine-ne edle aspiration from breast cancer patients, using a commercially avai lable amplification kit to demonstrate numerical chromosome alteration s of chromosome 17. In this staining procedure after detection of the biotin-labeled alpha-satellite probe for chromosome 17 with avidin-bio tin-peroxidase, we incorporated a signal amplification based on the pe roxidase-catalyzed deposition of a biotinylated phenolic compound foll owed by a secondary reaction with peroxidase. The reactions are reveal ed by deposition of diaminobenzidine and can be analyzed in an optical microscope, with total preservation of the morphology, allowing a dir ect morphologic-cytogenetic correlation. A series of 25 cases of aspir ates from breast cancer were analyzed with this methodology. Aneusomy was found in 14 cases (56%), whereas 11 (44%) had a normal number of c hromosome 17 copies. Polysomy occurred in all aneusome cases except on e. We did not find concordance between numerical chromosome abnormalit ies of chromosome 17 and nuclear grading as well as with the immunoexp ression of p53 and c-erbB2 studied in the smears. We conclude that the application of the ISH signal amplification method on alcohol-fixed s mears will eliminate the need for fresh material and will provide seve ral advantages, such as improvement of morphological concomitant analy sis without the need for a fluorescence microscope; utilization, whene ver malignancy is found, without necessity to reaspirate the patient: and adequacy of archival material. Diagn. Cytopathol. 1998;19:141-146. (C) 1998 Wiley-Liss, Inc.