Detection of chromosomal numerical abnormalities in clinical breast tumour fine-needle aspirations by fluorescence in situ hybridisation (FISH): refinement of a method.

This study sought to refine a fluorescence in situ hybridisation (FISH) technique for the study of numerical chromosome aberrations in cells recovered from breast tumours by fine-needle aspiration (FNA). Such techniques have been used to study numerical aberrations of chromosomes from tumours from many sites. This technique is intended for use in a routine cytopathology laboratory, and no specialised cytogenetics knowledge is necessary. Slide preparation, slide and probe denaturation, and stringency conditions were investigated. We found that the simplest slide preparation technique (direct smears) gave the best results. No difference was seen when slide and probe were denatured together or separately. Stringency conditions must be adapted to suit particular probes. Study of numerical chromosomal changes may help determine their significance in the clinical progression of the disease. Such changes may prove to have prognostic significance and therefore influence treatment of breast cancer. FISH on interphase cells is a technically straightforward, reproducible technique, suited to the study of numerical chromosome aberrations in tumour cells. The method has the potential for use in the study of malignant cells from sites other than breast, including ovary, prostate, lung and bladder.