Melanoma on the Rise in the U.S.
A combination of wearing protective clothing, avoiding the midday sun, and regular use of broad-spectrum, high sun protection factor (SPF) sunscreen are the best defense, according to Rigel and the American Cancer Society.
Parents should be particularly careful with children, Weinstock says. A recent nationwide survey of children ages 11 to 18 showed that many were developing sunburns despite using sunscreens of SPF 15 or greater, he says. "Prevention now will prevent problems later in their lives," he says.
Skin cancers are divided into two general types: melanoma and non-melanoma cancers, says the American Academy of Dermatology. The difference is what type of cells the cancers develop in.
The epidermis is the very thin outer layer of skin that protects the deeper layers of skin and the body's organs. Its outermost part is made up of dead cells called keratinocytes, which are continually shed. Below are layers of living keratinocytes, called squamous cells. The lowest part of the epidermis is formed by basal cells, which continually divide to form new keratinocytes.
Non-melanoma skin cancers -- usually basal cell (BCC) and squamous cell (SCC) cancers -- are the most common skin cancers, with more than 1 million new cases diagnosed every year in the U.S. When these cancers are detected and treated at an early stage, they are almost invariably cured. These types usually don't metastasize, or spread beyond the epidermis.
Melanoma, meanwhile, begins in the melanocytes, the cells that produce the skin coloring or pigment known as melanin. These cells are found in the base of the epidermis.
The six largest risk factors for developing melanoma are:
- Family or personal history of malignant melanoma
- Presence of blond or red hair
- Presence of marked freckling on the upper back
- History of three or more blistering sunburns prior to age 20
- History of three or more years of an outdoor summer job as a teen-ager
- Having unusual looking moles and/or an increase in the number of freckles on the body.
People with one or two of these risk factors have more than three times the risk for developing malignant melanoma, compared with the general population, Rigal says. Those with three or more of the factors have a 20-fold increased risk.