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In the last decade, a new method has emerged called 'network meta-analysis' to take into account all randomized trials in a given clinical setting to provide relative effectiveness between different treatments, whether or not they have been compared (pairwise) in randomized controlled trials. Network meta-analyses combine the results of direct comparisons from randomized trials with indirect comparisons between trials (i.e. when two treatments were not compared with each other, but have been studied in relation to a common comparator). The purpose of this note is to explain this method, its relevance and its limitations. A worked example in non-metastatic head and neck cancer is presented as illustration.

Meta-analyses of randomized trials using individual-participant data, which represent the highest level of evidence for the evaluation of a treatment effect, are now used in different contexts in clinical research. This article aims at reviewing some of these new applications. Meta-analyses are increasingly used in economic evaluation, which implies new measure outcomes of the treatment effect, as well as in biomarkers evaluations thanks to their higher statistical power and the possibility to validate findings on independent data. This article also considers the perspectives opened up by new data sources, such as randomized trials registers, and data sharing policies.

In the last decade, a new method has emerged called 'network meta-analysis' to take into account all randomized trials in a given clinical setting to provide relative effectiveness between different treatments, whether or not they have been compared (pairwise) in randomized controlled trials. Network meta-analyses combine the results of direct comparisons from randomized trials with indirect comparisons between trials (i.e. when two treatments were not compared with each other, but have been studied in relation to a common comparator). The purpose of this note is to explain this method, its relevance and its limitations. A worked example in non-metastatic head and neck cancer is presented as illustration.

A meta-analysis of trials addressing the same question is a quantitative synthesis of their results. Such a synthesis is useful when the overall result of these trials does not produce a clear answer. In oncology, the moderate effect of most available treatments explains the widespread use of meta-analyses. They are one of the way to reach a sufficient power. A meta-analysis provides a test for the efficacy of the treatment under study, and an estimation of this efficacy. To perform a meta-analysis, one must identify all the randomised trials addressing the question, whether their results have been published or not. The quality of a meta-analysis depends largely on the completeness of the collection of trials. A meta-analysis can be based on summary data or it can be based on individual patient data which allows intensive data checking, data corrections and update, and an intent to treat analysis. Individual patient data meta-analysis is the reference method. It is particularly useful for controversial questions, or when a small benefit is expected or when long-term follow-up is important, all these situations being frequent in oncology. It allows extensive analyses, for instance the study of the variation in treatment effect according to patient's and trials characteristics. Detailed verification of the data are essential since the inclusion of ill designed and ill conducted trials can only lead to a bad meta-analysis. Close collaboration with investigators is needed in this type of meta-analysis leading to large and rapid diffusion of the results. Meta-analyses and large-scale trials are complementary tools for treatment evaluation in oncology. Lastly, the large data bases of individual patient data meta-analyses allow subsidiary studies such as validation studies of surrogate endpoints or studies of the predictive value of tumour markers.

Lung cancer is the leading cause of cancer death in France. Nearly 80% of lung tumors are non-small cell lung cancers (NSCLC). Surgery is the best curative approach, but it only concerns 30% of NSCLC, since the diagnosis is frequently made in patients with locally advanced or metastatic disease. Even when surgery is performed relapse occurs in up to 50% of patients. Several adjuvant trials have been led in the late 90's after an individual data-based meta-analysis suggested a 5% survival benefit at 5 years. Among those, the IALT study, with 1 867 patients included, confirms the benefit of post-operative chemotherapy in resected NSCLC. In this article, the current status of adjuvant chemotherapy is reviewed, and future prospects are discussed.