Background This study was designed to evaluate if erythropoietin (EPO) is effective in the treatment of cancer related anemia, and if its effect remains unchanged when data are analyzed according to various clinical and methodological characteristics of the studies. We also wanted to demonstrate that cumulative meta-analysis (CMA) can be used to resolve uncertainty regarding clinical questions.

      Methods
      Systematic Review (SR) of the published literature on the role of EPO in cancer-related anemia. A cumulative meta-analysis (CMA) using a conservative approach was performed to determine the point in time when uncertainty about the effect of EPO on transfusion-related outcomes could be considered resolved. Participants: Patients included in randomized studies that compared EPO versus no therapy or placebo. Main outcome measures: Number of patients requiring transfusions.


      Results
      Nineteen trials were included. The pooled results indicated a significant effect of EPO in reducing the number of patients requiring transfusions [odds ratio (OR) = 0.41; 95%CI: 0.33 to 0.5; p  11.5 g/dl. We identified 1995 as the point in time when a statistically significant effect of EPO was demonstrated and after which we considered that uncertainty about EPO efficacy was resolved.


      Conclusion
      EPO is effective in the treatment of anemia in cancer patients. This could have already been known in 1995 if a CMA had been performed at that time.