Non interventional drug studies in oncology: Why we need them?

Oncology is a highly researched therapeutic area with an ever expanding armamentarium of drugs entering the market. It is unique in how the heterogeneity of tumor, patient and treatment factors is critical in determining outcomes of interventions. When it comes to decision making in the clinic, the practicing physician often seeks answers in populations with obvious deviations from the ideal selected populations included in the pivotal phase III randomized controlled trials (RCTs). While the randomized nature of the RCT ensures its high internal validity by removing bias, their 'controlled' nature casts a doubt on their generalizability to the real world population. It is for this reason that trials done in a naturalistic setting post the marketing authorization of a drug are increasingly required. This article discusses the importance of non interventional drug studies in oncology as an important tool in testing the external validity of controlled trial results and its value in generation of new hypothesis. It also discusses the limitations of such studies while outlining the steps in their effective conduct.