I've heard of different treatments, studies for oral leukoplakia, including chemoprevention, through the years. I'm not sure what are currently active or still applicable in this area, but a few were with Photodynamic Therapy (PDT), Tarceva an epidermal growth factor receptor, and chemoprevention with Vitamin A, and other retinoids, Beta Carotene, vitamin E and Selenium, biochemoprevention and others.

Through the years, there were also a number of reports regarding certain foods, extracts, medicines that were said "may" be beneficial, not that I'm promoting any, in reducing incidents of some head and neck cancers, pre-malignancies, so many that I lost count, such as with coffee, green tea, mushrooms, broccoli, curcumin or tumeric, metformin, etc.

I do believe a healthy lifestyle with absence from smoking, alcohol, chewing tobacco and other carcinogens, may help too, and maintaining a healthy immune system, and avoiding getting sick may help too.

I can't seem to copy some reports I saved by email, but you can google them, and I'm sure you'll find a number of them.