Difluoromethylornithine (DFMO) is a promising chemopreventive agent which is excreted unchanged in the urine, is active in vivo against superficial bladder cancer in animal tumor model systems, and has cytotoxic activity in vitro against superficial bladder cancer cells. Thus, DFMO may be particularly efficacious in preventing the development of bladder tumors and/or for the therapy of established superficial bladder cancer. To examine this hypothesis, an intergroup clinical trial is currently accruing patients with cystoscopically resected superficial bladder cancer (who would otherwise simply be observed). While the primary goal of this protocol is to define a daily dose of DFMO having little or no toxicity for use in future randomized chemoprevention trials, the rate of recurrent bladder tumors will also be followed in the hope that DFMO will inhibit the development of recurrent bladder cancers.