Anemia in Placebo Arms of Cancer Studies

Anticancer Res. 2021 Sep;41(9):4543-4548. doi: 10.21873/anticanres.15266.


Background/aim: Adverse event (AE) frequencies observed in interventional clinical trials are difficult to interpret when the placebo control is missing.

Materials and methods: Systematic literature review of AEs reported from the placebo arms of randomized cancer trials between 2008 and 2021. Imputation of missing values assuming normal distribution of hemoglobin values.

Results: Anemia grade 1 or higher was reported in 46 of 100 placebo monotherapy cohorts with a mean frequency of 23.4% (SD=27%) of the enrolled patients. The reported frequency depended on the type of cancer; other demographic variables had no significant influence on anemia frequency.

Conclusion: External controls for anemia in clinical trials should be disease specific.

Keywords: Meta-analysis; adverse events; cancer; oncology; placebo; randomized; systematic review.

Publication types

  • Systematic Review

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Anemia / chemically induced
  • Anemia / epidemiology*
  • Antineoplastic Agents / adverse effects*
  • Child
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neoplasms / drug therapy*
  • Randomized Controlled Trials as Topic
  • Young Adult


  • Antineoplastic Agents