The aim of this Phase 0 clinical study is to determine the oral bioavailability of sulforaphane in the commercially available dietary supplement, Avmacol®, and to determine the level of pharmacodynamic upregulation of NRF2 target gene transcripts that occurs in the oral epithelium of patients who have completed curative treatment for tobacco-related HNSCC, including high grade dysplasia, carcinoma in situ, or invasive carcinoma.