I would assume that a more likely scenario (although yours is also likely!) is someone with cancer will almost certainly search the internet at some point for information about cancer and their treatments. This will immediately be sucked up by the pervasive surveillance economy and used to extract the maximum amount of marginal revenue attainable through any means necessary. You don’t need to know they’re in a doctors waiting room, using the internet for information retrieval will specifically inform everyone interested in paying for it what you are searching for.