What has the meta-analysis contributed to today's standard of care in the treatment of thoracic malignancies?

Summary

Meta-analyses dealing with the treatment of thoracic malignancies (non-small cell lung cancer, small cell lung cancer and mesothelioma) are reviewed including those performed in the context of a systematic review of the literature or based on individual patients data.

Their results have been used as an effective tool for resolving various clinical questions, providing more reliable evidence for some clinical practice: (neo)adjuvant chemotherapy after surgery for resectable NSCLC, radiochemotherapy for patients with unresectable limited NSCLC and limited SCLC, advantage of chemotherapy for advanced NSCLC and identification of the most active drugs. However, it is important to understand the limits of their methodology in order to avoid inappropriate interpretations.

Introduction

Meta-analysis is a methodological technique allowing to obtain a quantitative synthesis of the numerical results of the outcomes of trials (usually, almost exclusively, randomised controlled trials), using standardised and agreed statistical methods. This kind of study can be necessary because the treatments effects are modest and that there are a need of huge number of patients to have statistically significant results. Three kinds of meta-analyses can be realised: systematic review of the literature with meta-analysis, isolated meta-analysis of literature and individual data meta-analysis. The systematic review of the literature is a methodological review, which analyse exhaustively the literature in order to respond to a precise question. The available data are qualitatively and quantitatively analysed. If the studies are homogeneous, the results aggregation is possible and the quantitative analysis is called meta-analysis. We call this type of study meta-analysis and systematic review of literature (MASRL). In the isolated meta-analysis (IMA), the literature is reviewed in order to respond to one question directed on the aggregation of the available results. There is no qualitative analysis but the meta-analysis must integrate all the publications available in the literature. In the individual data meta-analysis (IDMA), the data of each patient included in each study are collected, results are updated and finally results are aggregated [1].

The place of meta-analyses is becoming important in thoracic oncology as well as in epidemiology, aetiology, diagnostic, prognosis as in treatment. This review will only focus on the contribution of meta-analyses (published in medical journals) in the treatment of non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC) and mesothelioma. Meta-analyses were identified by an electronic search on the Medline data base, completed by a manual search in the articles. Only meta-analyses published in French, English, Spanish, Dutch and German were taken into account.