Suggest Treatment To Cure Vitiligo In Legs

sir,i am suffering from vitiligo.it happened at the age of 5 yrs.now i am 21 yrs old. i am taking uvb rays for its treatment 1days in a week,a good response has been seen in all parts of body except leg portion.the treatment is going on from 1 yrs ,what should i do for the leg portion.sir,i have heared that long treatment with uvb may cause skin cancer,so what should i do............