It would be of special interest if future GEP studies performed in large sample cohorts could validate our results and identify these categories as classifiers for bad prognosis. In many cases, the number of gene identifiers reported by the GEP study did not actually correspond to the annotated genes, but to probes on the expression array or GenBankIDs. Added to that, several studies counted some genes more than once. Therefore, the current number of annotated genes finally used was lower than the one reported by the majority of the GEP studies. In 1992, a team lead by Tom Chalmers and Fred Mosteller introduced the term ‘cumulative meta-analysis’ to describe a statistical procedure to calculate, retrospectively,GSK984 summary estimates based on the results of similar trials every time the results of a further trial in the series had become available. One of their two papers published in 1992 made clear how important this procedure was for auditing both research and healthcare advice. Comparisons of the results of cumulative meta-analyses of treatments for myocardial infarction with the advice that had been promulgated through medical textbooks made clear not only that research had continued long after robust estimates of treatment effects had accumulated, but also that medical textbooks had overlooked strong, existing evidence from clinical trials,CCF642 both of beneficial and of lethal effects of treatments. Cumulative meta-analyses have subsequently been used to assess what could have been known had the design of new studies been informed by reference to systematic reviews of relevant existing evidence and how these might have reduced waste. Cumulative meta-analyses emphasise the need for the design of new studies to be informed by existing research and for the results of new studies to be set in the context of updated systematic reviews of the relevant evidence from all sufficiently similar studies. The idea of using the accumulating evidence to make decisions about the design and ongoing conduct of trials is not new: the report of a case study published by Henderson and colleagues nearly 20 years ago noted.