High incidence of nuclear accumulation of p53 protein in gastric cancer.

The accumulation of p53 protein in the nuclei of cancer cells is known to correlate well with the presence of mutations in the p53 gene. We therefore investigated the immunohistochemical reactivity of the anti-p53 antibody, PAb1801, in specimens taken from 149 cases of primary gastric cancer and processed by acetone fixation, in order to elucidate the incidence and clinicopathological significance of p53 alterations in gastric cancer. Thirty-four out of 99 (34%) advanced gastric cancers and 11 out of 50 (22%) early gastric cancers showed positive reactions in the nuclei. The nuclei of non-cancerous cells, including gastric glandular epithelial cells, however, were not stained. Histopathologically, a nuclear accumulation of p53 protein was seen frequently in papillary adenocarcinoma, well- to moderately-differentiated tubular adenocarcinoma and poorly-differentiated adenocarcinoma with solid nests or focal tubular structures (43/101, 43%), but was rarely seen in signet-ring cell carcinoma, mucinous adenocarcinoma or poorly-differentiated adenocarcinoma growing in a scattered manner (2/48, 4%). There was no correlation between stainability of p53 protein and clinicopathological features such as depth of tumor invasion, microscopic lymphatic invasion, microscopic venous invasion, nodal involvement and clinicopathological stage in papillary adenocarcinoma, well- to moderately-differentiated tubular adenocarcinoma and poorly-differentiated adenocarcinoma with solid nests or focal tubular structures. The results suggest papillary adenocarcinoma, well- to moderately-differentiated tubular adenocarcinoma and poorly-differentiated adenocarcinoma with solid nests or focal tubular structures to share a common carcinogenetic pathway in which mutation of the p53 gene has an important role to play at a relatively early stage. Additionally, we showed the applicability of immunohistochemical detection of p53 protein in endoscopic biopsy material routinely formalin-fixed. The current method may be of some help in routine practice in discriminating between normal, precancerous and cancer cells in the stomach.