Thyroid transcription factor 1 - a new prognostic factor in lung cancer: a meta-analysis

Background: The aim of this study was to determine the prognostic role for survival of thyroid transcription factor 1 (TTF-1) in lung cancer. Methods: Studies evaluating survival and TTF-1 in lung cancer patients, published until August 2005, were assessed with a methodological scoring system. The required data for estimation of individual hazard ratios (HRs) for survival were extracted from the publications and a combined HR was calculated. Results: We identified 10 eligible papers, all dealing with non-small-cell lung cancer (NSCLC). Eight were meta-analysed (evaluable studies). Seven studies included patients with local and/or locoregional diseases and three dealt only with adenocarcinoma. Median methodological quality score was 65.9% (range = 31.8%-70.5%). TTF-1 positivity was associated with statistically significant reduced or improved survival in one and four studies, respectively. Combined HR for the eight evaluable studies was 0.64 [95% confidence interval (CI) = 0.41-1.00]. In the subgroup of adenocarcinoma, the combined HR was 0.53 (95% CI = 0.29-0.95). Conclusion: TTF-1 is a good prognostic factor for survival in NSCLC. Its effect appears also significant when the analysis is restricted to patients with adenocarcinoma. This study supports the fact that TTF-1 could be included in further prospective trials studying prognostic factors in NSCLC.