David L. Streiner, PhD, of McMaster University, Hamilton, Ont., and the University of Toronto, joins Blood & Cancer host David Henry, MD, of Pennsylvania Hospital, Philadelphia, to talk about meta-analyses and what they really tell us about the evidence for treatment.

Plus, in Clinical Correlation, Ilana Yurkiewicz, MD, of Stanford (Calif.) University, talks about when a second or third opinion can be detrimental in aggressive cancer.

This Week in Oncology

Show notes

• Meta-analysis: A systematic, thorough review of the literature, extraction of the effect sizes, and mathematical combination of effect sizes to produce an overall estimate.

• Analyses (both negative and positive trials) with larger sample sizes get more weight than smaller studies do. 
  • Example: Erythropoiesis-stimulating agents in oncology: A study-level meta-analysis of survival and other safety outcomes Br J Cancer. 2010; 102(2):301-15.
    • Analyzed 60 studies, including unpublished works.
    • Conclusion of the meta-analysis: Erythropoiesis-stimulating agents had no significant effect on the outcome of survival.

• Forest plots:
  • Null hypothesis = odds ratio of 1 means no difference between the two groups.
  • Squares on the right of the line favor control group.
  • Squares on the left of the line favor treatment group.
  • The size of the square corresponds with the sample size.

• Each meta-analysis is to be evaluated as an estimate of truth, but not truth itself.

Show notes by Emily Bryer, DO, resident in the department of internal medicine, University of Pennsylvania, Philadelphia.

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