The aim of this study was to investigate the frequency of p53 alterations in bilateral breast cancer and to evaluate a possible clonal relationship between the paired tumours regarding p53 alteration and other pathobiological variables. Tumours from 34 patients were investigated with immunohistochemistry, single strand conformation polymorphism analysis and DNA-sequence analysis applied to exons 5-8. Fifteen percent of the 68 tumours showed positive immunoreaction and/or presence of mutation. The occurrence of p53 accumulation was 9% and the prevalence of gene mutation 10%. No significant concordance was found between the tumours in the same patient for p53 alterations, progesterone receptor status or DNA ploidy. S-phase fraction showed a weak correlation, not statistically significant. Oestrogen receptor status was the only variable that exhibited a significant concordance. No convincing evidence was found for other associations between the paired tumours or for a high prevalence of p53 alterations in bilateral breast cancer.
