What Causes Senile Warts On My Midriff And Rib Area?

Hi, I have many senile warts and have had some frozen off before but I still have more coming all the time, they say its exposure to the sun but they dont grow where ive exposed my body to the sun they are on my midrif and rib area. Could they also be related to a vitamin or mineral deficiency and if so what is it.