Foi Halfway House, de Robert Silverberg .
Franco Alfieri is a very rich man, but the best doctors on Earth can't stop the cancer eating at his body. Fortunately, there are other worlds with advanced medicine. Alfieri applies to be sent through the Fold, an interdimensional rift, to a planet where his disease can be cured. But there is a price to be paid for such a privilege, and Alfieri's wealth will do him no good at all.