The skin is the largest organ of the human body. Skin cancer, as the name implies, is a type of cancer that occurs on the skin. It is relatively rare in our country, and generally Caucasians are more prone to develop it than other races, but this does not mean that yellow people do not develop skin cancer. Research points out that skin cancer is one of the common malignant tumors in China, and the vast majority of them grow on exposed areas. Since there are no obvious conscious symptoms in the early stage, if not treated early, it will cause local tissue erosion. The earlier skin cancer is detected, the easier it is to be cured; if it is detected at a later stage, it will be fatal. Therefore, it is very necessary to recognize the early symptoms of skin cancer. The typical symptoms of skin cancer in early stage are as follows: 1. Squamous cell carcinoma is often transformed from keratosis, mucous membrane white spots and other pre-cancerous diseases. It grows faster and forms ulcers at early stage. Some of them are nodular or cauliflower-like, with small invasion to the deep, and the base can be moved; some are butterfly-like, with more obvious infiltration to the deep, destructive, and often involving bones. Squamous cell carcinoma is often accompanied by purulent infection with foul smell and pain. 2.Basal cell carcinoma is often asymptomatic at the beginning, but at the beginning it is mostly a hard basal plaque-like papule, some of them are raised in the shape of warts, and then it breaks down into ulcers, irregular, with elevated edges, resembling craters, with uneven bottom and slow growth. The metastases are rare, but first occur as shallow ulcers with translucent nodular elevations on the edges, and then gradually expand and can erode the surrounding tissues and organs, becoming erosive ulcers. Malignant melanoma is a kind of skin cancer with high malignancy and rapid metastasis. It has a high prevalence rate and high mortality rate in western countries. Chinese people have more pigment in their skin and have better protection against ultraviolet rays, and also pay more attention to sun protection in daily life, so malignant melanoma is relatively rare in China. Since melanoma is black in color, it is relatively easy to detect. Therefore, if you find black spots on your nails, nail beds, feet, hands or other parts of your body, and they are obviously enlarged and easily broken in the near future, or half of your nails are blackened, you should be alerted and go to the hospital for examination in time. Then, how can we effectively prevent skin cancer? As we all know, cell phone has very high radiation, and in recent years, the International Agency for Research on Cancer has classified the radio frequency electromagnetic field used by cell phone as “possible carcinogen”, so it is recommended to avoid long time phone calls. 2.Less CT scan With the development of high technology, the first thing to do is to take a CT scan first, CT scan has a very large amount of radiation, the long-term accumulation of radiation will bring more harm to health, it is recommended to avoid some unnecessary CT scan. 3, drink more lemon tea lemon tea can prevent skin cancer, it is understood that if you add citrus fruit peel when making tea, drinkers will reduce the chance of skin squamous cell skin cancer by about 70%. Citric acid contained in lemons has the effect of preventing and eliminating skin pigmentation, so it is often used for whitening. 4, eat more garlic Garlic can help sterilize and prevent cancer. Some experts have found that the more garlic you eat, the less potential carcinogens in your body. This is because garlic contains one of the most important anti-cancer substances – allicin, but it should not be cooked at high temperature.