Donepezil and Vitamin E to Prevent Side Effects Caused By Radiation Therapy to the Head in Patients Receiving Treatment for Small Cell Lung Cancer

OBJECTIVES: * Compare the interval between completion of cancer treatment that included prophylactic cranial irradiation and onset of cognitive decline in patients with small cell lung cancer (SCLC) treated with donepezil and vitamin E vs placebo. * Determine the toxicity of donepezil and vitamin E in these patients. * Determine whether preserved cognitive function favorably impacts quality of life in these patients. * Determine the natural history of cognitive decline in these patients after cancer treatment. * Determine whether genotypes of apolipoprotein E predict decline in cognitive function among patients at risk for treatment-associated dementia and whether these genotypes predict duration of disease-free survival among patients who have achieved complete response after treatment for SCLC. OUTLINE: This is a randomized, double-blind, placebo-controlled study. Patients are stratified according to cognitive function (normal vs mild to moderate dysfunction vs severe dysfunction) and age (60 and under vs over 60). Patients are randomized to 1 of 2 treatment arms. * Arm I: Patients receive oral donepezil daily and vitamin E twice daily. * Arm II: Patients receive oral placebos according to the same schedule as the study drugs in arm I. All patients begin treatment within 2 weeks after completion of prophylactic cranial irradiation. Treatment continues for a minimum of 1 month in the absence of disease progression, unacceptable toxicity, or a 3.0 point drop on the Mini Mental State Examination (MMSE) and/or a 5 point drop on the Blessed Dementia Scale. Cognition is assessed using the Blessed Dementia Scale and the MMSE at baseline and then every 3 months during study. Quality of life and depression are assessed at baseline and then every 3 months during study. Patients are followed every 6 months.