New research from U. Minnesota has strengthened the link between indoor tanning and the risk of developing melanoma.

Using any type of tanning bed for any period of time may increase the likelihood of developing melanoma — the most deadly form of skin cancer — by 74 percent, the study said.

The study showed that frequent patrons of indoor tanning salons were 2 1/2 to three times more likely to develop melanoma than those who have never used indoor tanning beds.

The study defined frequent users as those who spent at least 50 hours, 10 years, or more than 100 sessions using a tanning bed.

“What is remarkable about our results are that they are very consistent,” said Dr. DeAnn Lazovich , an associate professor of epidemiology at the University and the principal investigator of the study.

These results fly in the face of past studies, which showed that using tanning beds increased the likelihood of developing melanoma by just 15 percent.

While previous studies suggested that the age of an individual is an important risk factor, Lazovich’s study indicated that frequency of use is the biggest determinant. Those who begin using tanning beds at a young age are likely to use them more frequently, she said.

“While the data has already been quite strong, there were parts of the question that were not answered to all of our satisfaction,” said Dr. Allan Halpern , a dermatologist at Memorial Sloan-Kettering Cancer Center in New York City.

“This study addresses them very well,” he said.

The study examined more than 2,200 Minnesotans — roughly half of whom were diagnosed with melanoma — and gathered information on their tanning habits and compared that data to the cancer-free control group.

“Doing it in Minnesota where we know we have a lot of indoor tanning use really makes a study like this possible,” Lazovich said.