Hi, Thanks for writing in. The following features are to be recorded to predict increased chances of your friend having a cancer in his mole. (i) sudden increase in size of the mole beyond 6 mm (ii) if the surface is appearing elevated (iii) irregular margins and borders (iv) any wound or pus formation without signs of acute inflammation (v) sudden growth of a tuft of hair on the mole (vi) sudden change in the color of the mole If any of the above features are there in the mole of your friend then please counsel him to visit the dermatologist and get a clinical examination done. If required the doctors will recommend a biopsy. Please do not worry.