Expression of epidermal growth factor receptor in primary colorectal adenocarcinoma predicts expression in recurrent disease

We tested the usefulness of epidermal growth factor receptor (EGFR) immunostaining in primary colorectal adenocarcinoma as a predictor for EGFR status of tumor recurrences in 33 primary tumors and distant recurrences (July 1994 to June 2005). Representative primary and recurrent tumor sections were stained using mouse anti-EGFR antibodies, and only membranous staining of malignant cells was recorded. Results were reported as negative (no staining), 1+ (positivity in <50% of cells), or 2+ (positivity in >50% of cells). Of 33 cases, 19 (58%) showed the same extent of immunopositivity in primary and recurrent tumors. Bivariate logistic regression analysis of primary tumors with 2+ vs those with negative or 1+ staining showed that the primary tumor status had a major predictive relationship with that of recurrence (odds ratio, 45.99; confidence limit, 4.0-524.9; P = .0021). The difference between the median time to recurrence of primary tumors with the various degrees of staining was not statistically significant. Our reporting method provides a useful correlation between the staining profiles of primary colorectal adenocarcinoma and recurrent disease. It is exceptionally reliable in predicting immunopositivity of a recurrence when more than 50% of cells of the primary tumor are immunoreactive.