OUTLINE: Randomized, double-blind study. Groups of 6 patients are randomly assigned in a 2:1 ratio to Arms I and II, respectively. Arm I: Chemoprevention. Lotion composed of T4 endonuclease V protein encapsulated in liposomes and suspended in phosphate-buffered saline in a hydrogel base, T4N5 Liposome Lotion, T4N5. Arm II: Control. Liposomes suspended in phosphate-buffered saline in a hydrogel base, Placebo, PLCB.