Serum p53 antibodies: predictors of survival in small-cell lung cancer?

Serum p53 antibodies have been shown to be a poor prognostic marker in resected non-small-cell lung cancer (NSCLC), but studies in small-cell lung cancer (SCLC) have been contradictory. We have studied the incidence of p53 antibodies in a large SCLC cohort treated at one oncology centre and correlated the results with survival. 231 patients (63% male, median age 65), diagnosed and treated for SCLC between 1987 and 1994 at The Royal Marsden Hospital NHS Trust, had sera stored pretreatment. All samples were tested for p53 antibodies (p53-Ab) using a standardized ELISA technique with a selection of strongly ELISA positive, weakly ELISA positive and negative samples being confirmed with immunoprecipitation. 54 patients were positive for p53-Ab (23%). The presence of a high titre of p53-Ab (titre ratio >5) appears to be associated with a survival advantage with a relative risk of death of 1.71 (95% CI: 1.14-2.58) in those without the antibody (P = 0.02). This study, the largest homogeneous group so far looking at p53-Ab in SCLC, suggests that p53 antibody detection may have a role in predicting outcome in this type of cancer.