While the past decade has seen the development of multiple new interventions to diagnose and treat cancer, as well as to improve the quality of life for cancer patients, many of these interventions have substantial costs. This has resulted in increased scrutiny of the costs of care for cancer, as well as the costs relative to the benefits for cancer treatments. It is important for oncologists and other members of the cancer community to consider and understand how economic evaluations of cancer interventions are performed and to be able to use and critique these evaluations. This review discusses the components, main types, and analytic issues of health economic evaluations using studies of cancer interventions as examples. We also highlight limitations of these economic evaluations and discuss why members of the cancer community should care about economic analyses.