OUTLINE: This is a randomized study. Patients are stratified according to age (at least 18 to under 50 vs 50 to 59 vs 60 to 69 vs 70 and over), number of prior skin cancers in past 5 years (2 vs 3 vs at least 4), time since most recent skin cancer occurrence (less than 12 months vs at least 12 months), sunburn susceptibility (none vs moderate vs high), visible skin damage (mild vs moderate vs severe).