1067 Background: Ten years ago, a systematic review of 4 randomised trials comparing longer with shorter chemotherapy duration in MBC showed a 20% reduction in the risk of death with more chemotherapy cycles, supporting the policy of prolonging treatment in the absence of progressive disease or unacceptable toxicity. Since this analysis, new studies on different chemotherapy durations have been reported, with conflicting results. With these premises, the aim of this study was to review all the available evidence on this subject. Methods: The criteria used to identify relevant studies, through literature search, were 1) randomised trials, 2) investigation of longer versus shorter chemotherapy duration, 3) overall survival data. Eight studies comprising 1,942 randomised patients were retrieved. Pooled estimates, based on published data, of overall survival HRs were obtained according to standard meta-analysis procedures. Sensitivity analyses were performed to examine whether the overall effect on survival was associated with study design (intermittent control arm vs not), number of chemotherapy cycles in the control arm (<4 vs >4) and co-administration of endocrine therapy. Results: Overall longer chemotherapy duration was associated with an 8% reduction in the risk of death (HR 0.92, CI 0.84–1.00; p 0.07). The magnitude of this effect was remarkably similar across groups of trials (table), suggesting its independence of study design, number of chemotherapy cycles in the control arm and concomitant endocrine therapy. Conclusions: The benefit associated with longer chemotherapy duration as first line treatment of MBC is, at best, marginal. Study subset Author, year HR 95% CI p Intermittent control arm Coates, 1987; Harris, 1990; Muss, 1991; Ejlertsen, 1993; French, 2000; Nooij, 2003 0.91 0.82–1.01 0.08 Nonintermittent control arm Gregory, 1997; Falkson, 1998; Gennari, 2006 0.94 0.76–1.16 0.56 Control arm < 4 cycles Coates, 1987; Harris, 1990; French, 2000 0.90 0.77–1.04 0.16 Control arm >4 cycles Muss,1991; Ejlertsen, 1993; Gregory,1997; Falkson,1998; Nooij, 2003; Gennari,2006; 0.93 0.83–1.05 0.22 Concomitant Tamoxifen Ejlertsen, 1993; Falkson,1998; Gennari,2006; 0.87 0.74–1.02 0.09 No concomitant Tamoxifen Coates, 1987; Harris, 1990; Muss, 1991; Gregory, 1997; French, 2000; Nooij, 2003 0.94 0.84–1.05 0.28 Overall All 0.92 0.84–1.00 0.07 No significant financial relationships to disclose.