To the Editor: Dr de Boer and colleagues1 performed an extensive review of an important issue for cancer survivors. They reported that cancer survivorship was significantly associated with unemployment. However, a large amount of heterogeneity was present in the analyses of this study, not only in the overall estimate but also in subgroup analyses for breast cancer, blood cancers, gastrointestinal cancers, and mixed cancer diagnoses. Heterogeneity indicates that the observed effects are more different from each other than one would expect due to chance alone.2 The presence of this large heterogeneity has considerable consequences for the validity of the study conclusions.
van Dalen EC, Kremer LCM. Employment Status Among Cancer Survivors. JAMA. 2009;302(1):32-35. doi:10.1001/jama.2009.905