P53 accumulation in primary breast cancer: a comparison between immunohistochemistry and a novel luminometric immunoassay.

The accumulation of p53 protein was evaluated by a novel luminometric immunoassay (LIA) in cytosol samples from a series of 245 primary breast cancers. The cytosolic p53 content was not related to nodal status or hormone receptor status, but it was significantly and directly associated with tumor size and cell proliferation. A matched comparison between immunohistochemistry (IHC) and LIA results of individual tumors showed a significant association, albeit with a correlation coefficient of only 0.41. The agreement of results from the two assays was higher in node-positive, estrogen-receptor-negative and rapidly proliferating tumors than in the complementary subgroups. Overall, there was a significant trend in favor of an increase in p53 levels as determined by LIA with the increase in p53-positive cells shown by IHC. However, taking IHC detection as a reference, the sensitivity of the LIA was better for negative (86%) than for positive (61%) values. Based on these findings, a comparative assessment of the clinical relevance of LIA versus IHC results has to be recommended.