The light-brown skin spots known as freckles are a part of life for most humans, some more than others. Those with the lightest complexions are most prone to developing these spots on areas of the skin that have the most contact with the sun's ultraviolet (UV) rays, indicating an increase in the skin's production of melanin. Freckles and cancer only rarely go together, particularly when they are the kind of the freckles called lentigines, which develop with severe sunburn.
Lentigines are slightly larger and darker than ordinary ephelide freckles, which are about the size of a nail head and light brown, pink or red in color. They also will not diminish over the winter as ephelides do. Other usually benign growths include liver spots and seborrheic keratoses that commonly develop on the skin of the elderly. None of these are necessarily cancerous. When any of these suddenly change in appearance, however, a doctor should be consulted.
When freckles and cancer go together, it is usually in connection with other more distinct features. Freckles alone usually will not signal cancer. Cancer on the skin will create lesions or abnormally large bumps. It also could show itself as a mole suddenly changing color, as in the case of melanoma. A doctor should be consulted, however, any time a significant change occurs in the color of freckles, even those located in an area with little exposure to the sun.
The ultraviolet light of the sun is blamed for creating freckles and cancer, though the former is not necessarily a precursor to the latter. According to the Mayo Clinic, this is only one cause, since it does not explain all the types of skin cancer that occurs on areas of the skin not typically exposed to the sun. Other factors leading to skin cancer include having fair skin, excessive sunburns, exposure to arsenic, a high number of lesions or moles, a genetic predisposition, and a compromised immune system. Though those with fair skin are more apt to exhibit freckles, this does not mean the freckles actually caused the cancer, just the sensitivity of the skin.
Doctors regularly suggest protecting the skin from UV rays by using a powerful sunblock, especially when spending several hours in direct sunlight. This helps to prevent both freckles and cancer from forming on the skin. Even with this protection, during the course of life, those with the lightest skin are most prone to have melanocytes — pigment-producing cells in the epidermis — overproduce to create freckles.