Cohorts of 6 patients receive escalating doses of EF5 until the maximum tolerated dose (MTD) or optimal dose is determined. The MTD is defined as the dose preceding that at which 2 or more patients experience dose-limiting toxicity. The optimal dose is defined as the dose level at or below the MTD and results in a signal-to-noise ratio of 75 or greater. Thirty additional patients are treated at the optimal dose.