Skin cancer affects more Americans than any other type of cancer, according to the National Institutes of Health. And with the sun’s strong rays upon us in summer, South Floridians should take extra caution in July and August.

“The incidence of skin cancer is about 3.5 million per year, or one in five Americans,” said Dr. Keyvan Nouri, professor of dermatology and cutaneous surgery at the University of Miami’s Sylvester Comprehensive Cancer Center.

“In Florida, that’s even greater due to the proximity to the equator and intensity of the sun,” said Nouri, director of Mohs micrographic surgery at Sylvester, a procedure used to treat common types of skin cancer.

There are three types of skin cancer: basal cell, squamous cell, and melanoma. While melanoma is the most deadly, basal and squamous cell carcinomas are much more common, according to Dr. Brian J. Katz, a dermatologist at the Miami Beach Skin Center. “About 75 to 80 percent are of the basal cell type. Squamous cell skin cancers are about 20 to 25 percent of skin cancers overall,” he noted.

These cancers originate in the skin’s top layer, the epidermis, and are named after the cells they affect, the basal cell or the squamous cell. Basal cells lie at the base layer of the epidermis, while squamous cells rest above this base layer. Overexposure to the sun’s radiation can result in the production of cancer cells, which divide and reproduce faster than average cells, according to the American Cancer Society.

Though skin cancer can affect anyone, people with light skin or a family history of skin cancer should be especially cautious, according to Dr. Eduardo Weiss, a dermatologist at Memorial Regional Hospital. People who have had organ transplants are also at high risk because of their weakened immune systems.

Because they are caused by cumulative sun damage, these cancers are often seen in older patients.

“The most important thing to remember is that 60 to 80 percent of sun damage happens in the first 20 years of the life, ” Weiss said. “Applying broad-spectrum, water-resistant sunscreens with an SPF of 15 or higher, wearing sun protective clothing and staying out of the sun at peak hours, between 10 a.m. and 4 p.m., is very important.”

Once a skin cancer has been contracted, the patient can detect it by paying attention to changes on the skin, according to dermatologist Dr. Betty Bellman, voluntary associate professor of dermatology at the University of Miami Miller School of Medicine. “The majority occur on sun-exposed areas anywhere from the hand to the chest to the face. You also should look at the top of the ear and the scalp, and behind the ear, because people don’t usually think to put sunscreen there,” Bellman said.

Basal cell carcinoma develops in three ways: nodular, superficial and infiltrative. Nodular basal cell carcinoma “appears as a fleshy colored bump, described as pearly and filled with blood vessels that break open and bleed easily,” said Miami dermatologist and Mohs surgeon at a private practice Dr. Eduard Gross, a voluntary professor of dermatology at the University of Miami. Superficial basal cell cancers run just along the skin’s surface, while infiltrative cancers grow as wispy strands within the skin. “Think of the difference between nodular and superficial cancers as the difference between a potato and the roots of a weed,” Gross said.