Converting epidemiologic studies of cancer etiology to survivorship studies: approaches and challenges

There are nearly 12 million cancer survivors living in the United States, and the number continues to rise with ongoing improvements in treatment and screening. Assuring the long-term health of these patients poses both clinical and public health concerns. Survivorship research covers multiple aspects of life after a cancer diagnosis, including quality of life, acute and late effects of cancer treatment and mortality. Answering these questions requires a wide array of data, including information on the outcomes of interest, treatment history, and lifestyle. One potentially efficient approach to studying late effects and survivorship is to convert or extend existing epidemiologic studies of cancer etiology. In this article, we evaluate the different potential approaches for doing this and the challenges this entails. Our evaluation highlights the combinations of research topic and design most likely to succeed. We show that any question that relates to the existing information including prediagnosis lifestyle factors or genetics (if samples are available) could be efficiently studied, with an appropriate design. On the other hand, most, though not all converted studies would be ill-suited to the evaluation of the effect of treatment and postdiagnosis lifestyle changes. In terms of endpoints, hard outcomes including mortality and second cancers are more likely to be available within the existing study framework than other morbidities or quality of life. In light of the costs and time required to build new cohorts, appropriately leveraging the existing studies offers an important opportunity to gain new insights into cancer survivorship for both clinicians and patients.