OBJECTIVES: I. Determine the minimal O6-benzylguanine (O6-BG) dose required to deplete tumor activity to less than 10 fmol/mg protein at a specified time after administration in patients with surgically resectable solid tumors. II. Correlate tumor tissue AGT depletion with AGT depletion in peripheral blood mononuclear cells (PBMC) obtained at a specified time after O6-BG administration in these patients.