Skin cancer is the most common form of cancer, with more than 3.5 million cases affecting more than two million people each year, according to the Skin Cancer Foundation. Early detection and treatment are key, which is why it's vital to pay attention to moles and other marks on your skin (and to see a dermatologist once a year for a skin exam).
There are three main kinds of skin cancer: Basal cell carcinoma, squamous cell carcinoma, and melanoma, the most lethal form (shown at left). In addition, there are "precancers" called actinic keratoses, along with iffy moles (dysplastic nevi) that could be worrisome. Keep clicking as Dr. Michele Green, a skin cancer expert in New York City, walks us through photos showing the things you should be looking for. The images are graphic, but looking at them just might save your life, or that of someone you love.