OUTLINE: This is a randomized, double-blind study. Patients are randomized no less than 2 and no more than 8 weeks after the last prior treatment modality received. Patients are stratified by participating institution. Patients are randomly assigned to receive either oral marimastat or oral placebo twice daily. Treatment begins within 5 days of minimization and continues for up to 18 months after the last patient is enrolled, unless disease progression or unacceptable toxicity intervenes. Patients deriving benefit at end of study may continue treatment if desired. Patients are followed every 3 months.