Ultraviolet light is a mutagen. That means that it causes changes in the DNA that controls the growth of cells and transforms them into cancer cells. Melanin is a pigment in the skin which absorbs ultraviolet radiation and protects the tissues in and below the skin. Darker skinned persons have more melanin than fairer skinned people. melanin is contained in cells called melanocytes. When a melanocyte becomes cancerous, it is called a melanoma.
Other types of skin cancers are basal cell cancers and squamous cell cancers--squamous cell cancers are by far the most common, but much less lethal than melanomas. These types of cancers are most often seen in elderly persons, and as with melanoma, are a consequence of sun exposure.
Austrialians have the highest rate of skin cancers in the world. Australia has only 0.3% of the world's population, but has 6% of the lethal skin cancers. This is thought to be because of the large number of fair-skinned people living in tropical conditions.
In their study, investigators at the NIH found that the incidence of melanoma in young men in the United States increased from 4.7 to 7.7 cases per 100,000 persons between 1973 and 2004. In young women over the same time period, the incidence increased much more rapidly from 5.5 to 13.9 cases per 100,000. Probably because young women are much more likely to purposefully seek out exposure to sunlight or tanning beds.
The good news is that the number of deaths as a consequence of melanoma among young men and young women has decreased from 1981 onward. This is likely due to both an increased awareness about melanoma and changes in screening techniques.
In Australia, an interesting new technology called Solar scan has been recently developed. The key to Solar Scan is advanced computer software. A camera is pointed at a suspicious lesion and photograph is taken, stored, and analyzed by the software. Not only can Solar Scan make a quick diagnosis, it can collect images and compare data over a period of time allowing doctors to monitor suspicious lesions for change.
Staying out of the sun and/or tanning booths is the best way to protect yourself from skin cancer. If that is not possible, wearing sunproof clothing is the next best option. Suntan oils and lotions protect the skin by reflecting or absorbing ultraviolet rays, and are definitely adviseable if sun exposure is contemplated.
Signs and symptoms of melanoma include a new spot appearing on the skin, a spot that grows in size or changes color or shape. Itching and bleeding are also important symptoms. Any spot that is larger than 6 millimeters, or is irregular in color, or shape, should be evaluated by a physician. A Dermatologist is the type of doctor to consult for anyone worried about a spot, or simply wishing to have a thorough skin evaluation.
One more interesting fact about melanoma: it is the most common cancer to spread across the placenta in a pregnant woman.