Experts from Beijing Cancer Hospital say that although there are no national surveys as yet, numbers in Beijing and Shanghai show that the incidence rate of melanoma is five times higher than it was five years ago, and one out of every 100,000 people in these two cities have skin cancer. 

All cancers are caused by DNA mutations, which can be inherited but in most cases are built up over a person's lifetime by environmental factors. In the case of skin cancer, ultraviolet rays (mostly ultraviolet-B in sunlight) are the most threatening environmental factors.  

Darker skin has a stronger ability to absorb ultraviolet rays, which serves as a natural defensive mechanism the skin uses to protect itself from skin cancer. That is why the incidence rates of skin cancer vary among races: white people have the highest skin-cancer incidence rate in the world, while black people the lowest, and Asians in the middle.