Radiation therapy is commonly used as a treatment for tumors. What we see is the darkening of the skin, but in the actual radiotherapy, the darkening of the skin is gradually deepened, just like sunbathing. As the color of radiotherapy deepens, the skin may gradually become darker, and the pigmentation may start with spots and then gradually become darker, and then the skin may break out in severe cases. Theoretically, the degree of sensitivity varies from person to person, some people may only have darkened skin, some may not have changed their skin, most people have changed their skin during radiotherapy, but the degree of change varies, from a small redness to a slow darkening of the skin, or even a breakout of the skin. With the increase of radiation therapy technology and the precise control of radiation therapy, the skin darkening including ulceration is less and less, and more often the skin is lightly reddened. Radiation therapy is actually the same as sunbathing, except that the energy of radiation is different from the normal ultraviolet energy, and its principle is actually the same as the formation of skin pigmentation by sunlight. Therefore, radiotherapy for skin darkening do not care too much, it is a transient reaction, will not have much impact, but for skin ulcers need to be treated; another is the skin darkening, sometimes in the treatment process can be prevented by drugs, relatively speaking, treatment is not possible without darkening, but the relative chances are becoming less, so we do not have to worry too much about this matter.