President George W. Bush recently had four skin lesions removed from his face, two of which could have turned into non-melanoma skin cancer if left untreated, the White House announced this week.

Lesion is the term doctors use to describe an abnormal growth of tissue, and there are many kinds.

The two lesions President Bush had removed that could have turned cancerous were actinic keratoses, small abnormal skin growths caused by too much exposure to ultraviolet (UV) light, usually sunlight.

The other two lesions — seborrheic keratoses — do not usually turn cancerous and are the result of excessive growth of cells in the outer layer of skin.

The two actinic keratoses were on the President's cheeks. One of the seborrheic keratoses was on his temple, and the other on his forehead.

Actinic keratoses usually appear as slightly raised, pink or red scaly-looking or rough patches on sun-exposed skin.

Left untreated, actinic keratoses can turn into squamous cell skin cancer, one type of non-melanoma skin cancer. But treatment prevents that, said a dermatologist familiar with skin cancers.

"Actinic keratoses are very common but also very easy to treat, without any cutting," said Martin Weinstock, MD, PhD, at Brown University and the VA Medical Center in Providence, R.I.

Weinstock, chair of the American Cancer Society (ACS) skin cancer advisory group, says actinic keratoses usually are frozen off with liquid nitrogen in a doctor's office, but can also be treated with creams or other methods.

A bright red spot on each cheek indicated to observers that the President likely had the actinic keratoses frozen off.

UV light can come from tanning lights, but most people who develop actinic keratoses get exposure to UV light by spending time in the sun without adequate sun protection, and the lesions are more common in the South, said Weinstock.

President Bush has been active outdoors for many years, much of that time in the years before sun protection was thought to be as important as it is now known to be.

The President still spends time outdoors, especially at his ranch in Crawford, Texas, but now routinely uses sunscreen, said a White House statement released on Dec. 17.

Bush also wears a wide-brimmed hat while he works on the ranch, according to White House officials.

Weinstock notes that both of those practices are good ones, and that studies have shown using sunscreen can also reduce the number of new actinic keratoses developing in people exposed to excessive sunlight in the past.

And sunscreen can cause some actinic keratoses that have already developed to go away as well, Weinstock explained.

Skin cancer is one of the most preventable cancers if a person knows their risk factors, and uses preventive measures, and has regular checkups, he added.

Weinstock said doing those things can help most people avoid sun damage that can both prematurely age their skin and raise their risks of melanoma and the several kinds of non-melanoma skin cancer.

"If you're going out in the sun, slip on some protective clothing, slap on a hat, and slop on some sunscreen," said Weinstock.

"The American Cancer Society calls that 'Slip, Slap, Slop,' and together with regular skin checkups, it really can save your life," said Weinstock.