Data sharing in clinical trials: An experience with two large cancer screening trials

Broad sharing of clinical trial data is important for ensuring reproducibility, transparency, and maximal use of the data by the research community. However, in practice, such data sharing typically requires planning, effort, and resources. Here, we describe a web-based data sharing system, the Cancer Data Access System (CDAS), developed for two large cancer screening trials: the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial and the National Lung Screening Trial (NLST). Deidentified individual participant data were organized into standard datasets readily downloadable from CDAS via a simple web-based application process that involves minimal scientific review. CDAS provides a "one-stop shop" for access requests, review, and data downloads. Since the launch of CDAS in November 2012 and through October 2016, 215 requests were received for PLCO data, of which 199 (93%) were approved, and 240 requests were received for NLST, of which 216 (90%) were approved. The estimated cost of CDAS was around US$300,000 for the initial development, plus additional maintenance and user-support costs of about US$26,000 per month. Because of its modular nature, additional studies can be added to CDAS with relatively little additional cost.