Researchers point to indoor tanning habits as a major driver of an alarming surge in melanoma, the most deadly type of skin cancer, among young women over the past two generations.

Skin cancer is the most common malignancy in the United States, with one in five people expected to develop it during their lifetime. The best way to reduce skin cancer risk is to limit exposure to ultraviolet (UV) light, whether from the sun or indoor tanning machines.

Laurin Council, MD, an associate professor of dermatology at Washington University School of Medicine in St. Louis, presented findings from an analysis of skin cancer trends at the 2019 American Academy of Dermatology Summer Meeting in New York last month.

Between 1970 and 2009, the melanoma diagnosis rate increased 9-fold among women 18 to 39 years old, elevating it to the second most common cancer diagnosis in this demographic. During a similar period, rates of basal cell and squamous cell carcinoma, two other forms of skin cancer, rose 2.5-fold and 4.6-fold, respectively.

Data indicate that exposure to UV light is on the rise in the United States, especially among white girls and young women.

“Because there’s a delay between UV exposure and when skin cancer appears, most women don’t think it will happen to them,” Council said in a press release. “This data reveals the disproportionate rise in the number of skin cancers in women and the need for further education regarding UV exposure.”

Researchers estimate that indoor tanning may cause more than 400,000 cases of skin cancer annually in the United States. A total of 7.8 million women use tanning devices each year, compared with 1.9 million men. Of women who started indoor tanning when they were younger than 15 years old, 54% did so with their mother.

Using a tanning device even once can increase an individual’s lifetime risk of melanoma by 20%, squamous cell carcinoma by 67% and basal cell carcinoma by 29%. The risk is magnified among those who use tanning machines when they are young. In particular, indoor tanning among those younger than 35 years old can increase the risk of melanoma by 59%. Successive use magnifies the risk.

“It’s important that young people understand the potential impact of the habits they form when they are younger,” Council said. “There are serious, long-term consequences to activities such as sunbathing and using indoor tanning devices.”