Treatment of data Data storage, management, and analysis will be centralized. An electronic database will be constructed to collect the data. The program will be distributed to all participating centers and the data will be entered at the time of the encounters with the subjects such as at the time of endoscopy for stent placement, follow-up visit, or follow-up telephone call. Randomization assignment (stent type) will be coded. Standard operating procedures for regularly backing up the data will be employed at each facility and centrally.