Variations associated with the DNA analysis of multiple fine needle aspirates obtained from breast cancer patients

The present study was carried out to determine the variation in DNA content between multiple fine needle aspirates (FNA) of the same tumour from patients with breast cancer. Analysis of different aliquots of the same FNA showed good reproducibility in terms of cell cycle distribution and DNA index. Duplicate FNAs taken from different sites in nine of 11 excised tumours showed similar reproducibility. However, two of the aneuploid tumours displayed substantial variations in the distribution of cell populations between the duplicate samples. Sequential FNAs with no intervening therapy were obtained from the same tumour in 17 patients; one at the time of diagnosis and the other at biopsy 1-3 weeks later. Only five cases showed no variation between the sequential FNAs; the remaining 12 displayed different DNA profiles. A further 13 patients were studied before and during systemic therapy. While there was no variation between sequential FNAs in four patients, marked differences in the DNA profile were observed in the remaining nine patients undergoing treatment, the changes not necessarily being associated with clinical response to therapy. It is concluded that the monitoring of cellular changes by DNA analysis of sequential FNAs may be complex and subject to problems associated with heterogenecity.