Quantitative chemiluminescent immunoassay of p53: prognostic significance in 220 node-negative breast cancer tissue.

The prognostic and predictive role of p53 overexpression in breast cancer samples is usually investigated by using molecular biology or immunohistochemical methods. However, the results are to date controversial, and this is in part due to the methodological pitfalls of both the methods. To study the possibility of overcoming, at least in part, these problems we evaluated a commercially available chemiluminescent immunoassay with which the p53 concentrations of 220 specimens from node negative breast cancer were determined. The assay showed good analytical performance and found detectable levels in 84.7% of cases (median 0.22 ng/mg of proteins, range 0-50 ng/mg of proteins). p53 has been found inversely correlated with estrogen receptors and directly correlated with cathepsin D. The prognostic role of p53 was evaluated in two different ways: a) two previous studies (Borg et al 1995, DeWitte et al. 1996) using the same method found almost 30% of samples had significantly shorter DFS and OS. We subdivided our cases in order to identify the same positivity rate and to verify if the previous cathegorizations were effective also in our patient series. We confirmed the independent association with DFS (p = 0.006) and OS (p = 0.0005); b) considering that any categorization of quantitative parameters could cause a loss of clinical information, we also evaluated p53 as a continuous variable. Multivariate analysis showed a significant quantitative relationship between p53 and both disease free (p = 0.026) and overall survival (p = 0.02).

c-erbB-2/neu protein expression, DNA ploidy and S phase in breast cancer.

DNA content and c-erbB2/neu protein (p185) expression were evaluated by flow-cytometry and ELISA, respectively, in 166 specimens of primary breast cancer. A non-diploid DNA content was found in 88 tumours (53%), with the DNA index ranging from 0.7-2.7. S phase fraction (SPF) evaluation, performed in 130 cases, showed significantly higher values in aneuploid than in diploid tumours (median values, 17.3% and 5.8%, respectively). Thirty-six tumours (21.6%) showed p185 overexpression, while 45 (27.1%) and 85 (51.3%) showed intermediate and low expression, respectively. A good correlation (P = 0.0023) was found between DNA content and p185 positivity. Tumours with high p185 values were mainly aneuploid, while tumours with intermediate or low expression had variable degrees of DNA content. Furthermore, p185 concentration was significantly higher in aneuploid than in diploid tumours (P = 0.009). The highest rate of p185 (+) cases and the highest p185 concentrations occurred in triploid (1.3 < D.I. < or = 1.7), compared to the other tumours. SPF values and p185 positivity rates were not significantly correlated in diploid and in aneuploid tumours.