The symptoms of cancerous moles are not always noticeable. If you develop a mole anywhere on your body and doubt that it might be cancerous, you need to look out for the following warning signs and symptoms. To begin with, the color of cancerous moles might change, and would usually become darker. Other symptoms include changes in the shape or size of the mole, change in texture of the mole and the number of moles on the skin might increase drastically. In addition, the location of the moles might signify a risk of their being cancerous – if they are on the breasts, beneath the hair or on the buttocks. In some cases, a risk factor of cancer could be if the moles are oozing, bleeding or are on itchy or inflamed scaly skin. If the mole is bigger than the diameter of a pencil eraser, or if the edges are uneven or irregular, or if the mole seems rough to the touch, or if it seems odd in any way it would most definitely need to be checked. On an average, a person has between 10 and 40 moles on their body. If this number begins to increase and if the number of moles reaches anywhere near 100, then this is a sign of cancerous moles.