OUTLINE: This is a randomized, double-blinded, placebo-controlled, multicenter study. Participants are stratified according to smoking status (actively smoking or stopped less than 1 year ago vs. stopped at least 1 year ago vs. never smoked or no more than 100 cigarettes ever), gender, and stage and previous therapy (stage IA vs. stage IB with previous therapy vs. stage IB with no previous therapy). Participants are randomized in a 1:2 ratio to arm I and arm II.