OBJECTIVES: I. Determine the maximum tolerated dose of oral phenethyl isothiocyanate in smokers. II. Measure the steady state pharmacokinetics of phenethyl isothiocyanate required to maintain a steady state of this substance during the hours of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) exposure in these patients. III. Obtain preliminary data on the perturbation of NNK metabolism by phenethyl isothiocyanate in these patients.