The role of p53, as a prognostic factor for survival in lung cancer, is controversial and the purpose of the present systematic review of the literature is to determine this effect.Published studies were identified with the objective to aggregate the available survival results after a methodological assessment using a scale specifically designed by the European Lung Cancer Working Party (ELCWP). To be eligible, a study had to deal with p53 assessment in lung cancer (primary site) only, and to provide a survival comparison according to the p53 status.Among the 74 eligible papers, 30 identified p53 abnormalities as a univariate statistically significant poor prognostic factor and 56 provided sufficient data to allow survival results aggregation. There was no significant difference between the trials that either showed or did not show a prognostic effect of p53 according to the methodological score or to the laboratory technique used. The studies were categorized by histology, disease stage, treatment and laboratory technique. Combined hazard ratios suggested that an abnormal p53 status had an unfavourable impact on survival: in any stage nonsmall cell lung cancer (NSCLC) the mean (95% confidence interval) was 1.44 (1.20-1.72) (number of studies included in the subgroup was 11), 1.50 (1.32-1.70) in stages I-II NSCLC (n=19), 1.68 (1.23-2.29) in stages I-IIIB NSCLC (n=5), 1.68 (1.30-2.18) in stages III-IV NSCLC (n=9), 1.48 (1.29-1.70) in surgically resected NSCLC (n=20), 1.37 (1.02-1.85) in squamous cell carcinoma (n=9), 2.24 (1.70-2.95) in adenocarcinoma (n=9), 1.57 (1.28-1.91) for a positive immunohistochemistry with antibody 1801 (n=8), 1.25 (1.09-1.43) for a positive immunohistochemistry with antibody DO-7 (n=16), and 1.65 (1.35-2.00) for an abnormal molecular biology test (n=13). Data were insufficient to determine the prognostic value of p53 in small cell lung cancer.In each subgroup of nonsmall cell lung cancer, p53 abnormal status was shown to be associated with a poorer survival prognosis. Lung cancer is the most common cause of cancer death in industrialized countries and its incidence is steadily increasing in females and in many European countries. Despite improvements in diagnosis and therapy, the overall 5-yr survival is still 15%.Some independent prognostic factors have been identified for predicting survival and helping in the management of patients with lung cancer [1]. They include: for small cell lung cancer (SCLC), extent of disease and performance status (PS) [2]; for resectable nonsmall cell lung cancer (NSCLC), PS, tumour, node, metastasis (TNM) stage, and age [3]; for advanced NSCLC, PS, TNM stage, age, sex and weight loss [4,5]. Among biological factors, white blood cell count, serum lactate dehydrogenase level, angiogenesis and factors reflecting proliferative state have been shown to significantly predict outcome [6,7].Recent progresses in molecular biology have allowed for the extension of the research on prognostic factors to the analysis of proteins and genes involved in cancer...