BACKGROUND.
Although several studies have been conducted to examine the role of p53 genetic abnormalities and their prognostic value in colorectal carcinoma, the incidence of nuclear accumulation of p53 and the prognostic importance of nuclear accumulation of p53 in African-American and white patients have not been investigated separately. Therefore, the authors evaluated the prognostic significance of p53 nuclear accumulation in these two racial groups.
METHODS.
Nuclear accumulation of p53 was evaluated immunohistochemically in archival tissue specimens from 204 African-American and 300 white patients with primary colorectal adenocarcinomas who had undergone surgery. Survival times from colorectal adenocarcinoma were analyzed using Kaplan-Meier survival estimates and the Cox proportional hazards model for nuclear accumulation of p53 with adjustments for other confounding demographic and clinical variables.
RESULTS.
Approximately equivalent proportions of distal (54%) and proximal adenocarcinomas (47%) were positive for nuclear accumulation of p53 in African-American patients. In contrast, distal colorectal adenocarcinomas from white patients more frequently were positive for nuclear accumulation of p53 than adenocarcinomas of the proximal colon (63% vs. 38%, respectively). Nuclear accumulation of p53 was found to be a strong predictor of poor survival in white patients (hazard ratio Ο 6.77; P Ο 0.0001) but not in African-American patients with primary adenocarcinomas of the proximal colon. Nuclear accumulation of p53 was not of prognostic value in patients of either race with primary adenocarcinomas of the distal colorectum.
CONCLUSIONS.
Nuclear accumulation of p53 is a valuable indicator of poor prognosis only for white patients with adenocarcinomas of the proximal colon. The current study also suggests that the role of p53 dysregulation in colorectal adenocarcinomas may vary with the anatomic location of the tumor and the race of the patient. These findings suggest that the demographic characteristics of patients should be considered in the evaluation of prognostic markers of colorectal neoplasia.