Purpose: The present study explores p53 in relation to the following four aspects of node-negative breast carcinoma: epidemiologic risk factors, tumor histopathology, prognosis, and HER2/neu (HER) expression.
Materials and methods: Immunohistochemical (IH) staining for p53 was performed on formaldehyde-fixed, paraffin-embedded primary invasive carcinomas from 440 node-negative patients with a median follow-up duration of 119 months.
Results: The IH expression, or lack thereof, of p53 separately or in combination with HER did not prove to be prognostically significant and there was no consistent association of p53 with epidemiologic risk factors. p53 was expressed in 68% of medullary carcinomas (MEDs), which is a significantly higher frequency (P < .001) than in lobular (9%) and duct (23%) carcinomas. p53 was not found in some types of low-grade carcinomas (tubular and papillary), and was observed in a minority of mucinous carcinomas. p53 was present significantly more often in carcinomas with high-grade or poorly differentiated nuclear grade than in low- or intermediate-grade tumors. There was an inverse statistically significant relationship between estrogen receptor (ER) positivity and p53 expression. Tumors with the p53(+)/HER(-) immunophenotype tended to be MEDs or duct carcinomas with a marked lymphoplasmacytic reaction. Infiltrating lobular carcinomas (IFLCs) were largely p53(-)/HER(-). p53(+)/HER(+) carcinomas had the best prognosis. The poorest outcome was associated with the p53(-)/HER(+) immunophenotype. This trend was statistically significant for recurrence-free and overall survival in patients with T1NOMO infiltrating duct carcinoma (IFDC).
Conclusion: The IH demonstration of p53 was not a reliable prognostic indicator in the node-negative breast carcinoma patients studied and it was not associated with major epidemiologic risk factors. The combined immunophenotypic expression of p53 and HER was significantly associated with some histologic types of breast carcinoma and with prognosis in T1NOMO breast carcinoma.