Microsatellite abnormalities in plasma of patients with breast carcinoma: concordance with the primary tumour

Aims-To detect microsatellite abnormalities in the primary tumours and plas ma of patients with breast carcinoma. Methods-Plasma was obtained from 17 breast carcinoma patients before surger y. Corresponding tumour and benign lymph node (control) samples for each of the carcinoma patients were obtained from paraffin blocks. DNA was extract ed from the plasma samples and the paraffin embedded tissue using previousl y described methods. Results-The 17 primary tumours showed two examples of loss of heterozygosit y and three examples of microsatellite instability; the 17 plasma samples s howed three and one, respectively. Many of the longer microsatellites lover 200 base pairs) were difficult to amplify from plasma. The investigations suggested that this was because of the highly fragmented nature of plasma D NA. Only one example of loss of heterozygosity and one example of microsate llite instability showed a concordant pattern in both primary tumour and pl asma. These were both in the same patient. Conclusions-DNA mutations concordant with those in the primary carcinomas c an occasionally be detected in the plasma of patients with breast carcinoma . However, the frequency would have to be markedly improved before this cou ld be of any diagnostic value.