Caucasian women who've experienced a minimum of five episodes of sunburn before age 20 face an increased chance of developing the fatal cancer of the skin known as melanoma, a study indicates.

The study analyzed 20 years' worth of data on more than 100,000 Caucasian nurses between the ages of 25 and 42 who were taking part in Nurses' Health Study II.

In initial interviews they were quizzed about known measured risk factors for skin cancers including frequency of sunburn exposure, the quantity of skin moles on their legs, and any family history of skin cancer.

Since the study participants were drawn from 14 different states, a corrected total ultraviolet (UV) light exposure for each woman, based on the time she lived in a given location, was calculated by the researchers.

Every two years the information on the nurses was updated.

Of the more than 100,000 nurses, 6,955 were diagnosed as having basal cell carcinoma, while 880 showed signs of squamous cell carcinoma and 779 had developed melanoma, the researchers reported.

Invasive cancer was found in an additional 445 of the nurses diagnosed with melanoma, they said.

Of the study participants, 10 percent reported having at least five blistering cases of sunburn between the age of 15 and 20.

Those nurses had a 68 percent increased risk of a diagnosis of squamous cell carcinoma or basal cell carcinoma, the researchers determined, while the risk of melanoma rose to 80 percent for the "sunburn group."

"Our results suggest that sun exposures in both early life and adulthood were predictive of nonmelanoma skin cancers, whereas melanoma risk was predominantly associated with sun exposure in early life in a cohort of young women," said Abrar A. Qureshi of the Department of Dermatology at the Brown University and Rhode Island Hospital in Providence.

However, the researchers said, a history of sun exposure did not uniformly correlate with any particular form of the most common skin cancers seen in the U.S., suggesting different pathophysiology might be at work in the different types.

Still, Qureshi said, links are strong enough to suggest caution for people susceptible to effects of sun exposure.

"An individual's risk of developing skin cancer depends on both host and environmental risk factors," Qureshi said. "Persons with high host-risk traits, such as red hair color, higher number of moles, and high sunburn susceptibility, should pay more attention to avoid excessive sun exposure, especially early in life."

Parents should be aware of the possible effects and should attempt to limit the sun exposure of their children, he suggested.