There are two primary categories of skin cancer: melanoma and non-melanoma. Melanoma skin cancers primarily affect pigmented types, and occur when the pigment cells that produce skin color become cancerous.
Consider whether you have any of the traits that predispose people to melanoma:
Freckled skin: In particular, those with fair skin and freckles are at a higher risk for melanoma. The gene that causes freckles, MC1R, also seems to play a role in melanoma formation.
Red hair: That MC1R gene? It also contributes to the development of red hair.
History of damage: If you sunburn easily, or have a history of many sunburns, pay particular attention to changes in your skin.
Family history: If anyone in your family has been diagnosed with melanoma, you are at greater risk for developing it.
The most important thing you can do is familiarize yourself with the map of your body's beauty marks and freckles - that way, you can note any changes or fast-growing moles. If you notice one of the A, B, C, or Ds of melanoma, see a dermatologist right away:
Asymmetry: Moles of an irregular shape, in which one side is not the mirror image of the other
Borders: Moles that have a fuzzy or indistinct border
Color: Moles that are more than one color, or include black, white, red, or yellow hues
Diameter: Moles that are larger than a quarter-inch (about the diameter of a pencil eraser)
Like melanoma, non-melanoma skin cancer tends to affect fair-skinned people more than others, although in this case non-pigmented types are at greater risk than pigmented types.
There are two main types of non-melanoma skin cancer:
Basal cell carcinoma (BCC): This type of skin cancer occurs between the dermis and the epidermis. It appears as bumps that are white, shiny, and luminous like a pearl. They can appear with a raised center or like "craters," and may also have tiny blood vessels around their borders. Also, if you notice a scar-like mark on your skin in an area where no injury or trauma has occurred, have it looked at immediately. Sometimes it looks like a translucent bump with a central umbilication or an enlarged pore that suddenly appears.
Squamous cell carcinoma (SCC): This type of skin cancer occurs on the top layer of skin, in sun-exposed areas. It appears as a red, scaling patch that scabs over - unlike a scab, however, these patches don't heal. They may also be covered by a hard white scale.
Early detection is crucial in treating skin cancer. Have annual skin checks, during which your dermatologist can look for any unusual moles or marks (if you have a family history of melanoma or are particularly predisposed to developing it, biannual checks are best). And if you see any suspicious bumps or scabs - particularly those that fit the descriptions above - don't hesitate to see a doctor right away.
(Taken from Yahoo Health)