Non-melanomas are the most common type of skin cancer. They include basal cell carcinomas and squamous cell carcinomas. There are other types of non-melanomas, but basal cell and squamous cell account for the most non-melanomas. Basal cell carcinomas comprise eight out of 10 cases of non-melanomas and usually show up in areas where there has been a lot of sun exposure. Squamous cell carcinoma accounts for about two in10 cases of non-melanoma and appears on sun-exposed skin, but it can be present in scars or chronic skin sores. 

Know your ABCDEs 

There are simple ways to spot potentially troublesome moles or lesions that could be cancerous. Knowing your ABCDEs -- asymmetry, border, color, diameter, evolving. 

Asymmetry is an unevenness of the mole. If you draw a line through the middle of the spot, it should be symmetrical, or the same on both sides. If it's not the same on both sides, the mole is asymmetrical and may be cancerous. 

Borders of a normal mole or freckle are usually even. The borders of an early melanoma tend to be crooked or scalloped.