Melanoma among younger individuals is on the rise, and now new research suggests that initiating indoor tanning at an earlier age and more frequent tanning may be to blame.

In the study, women younger than 40 when diagnosed with melanoma reported initiating indoor tanning at an earlier age and more frequent tanning than older women diagnosed with the skin cancer.

The findings appear online in JAMA Dermatology.

The study included 681 patients from Minnesota diagnosed with melanoma between 2004 and 2007 and 654 comparison patients aged 25 to 49. Among the patients with melanoma, 68.3 percent were women as were 68.2 percent of the patients in the comparison group.

Women who tanned indoors had between a two times to six times increased risk of developing melanoma, the study suggests.

Compared with women 40 to 49, women younger than 40 reported initiating indoor tanning at a younger age (16 vs. 25 years old) and they reported more frequent indoor tanning (median number of session, 100 vs. 40), according to the results. About 33 percent of the women (21 participants) diagnosed before the age of 30 had melanomas on their trunk compared with 24 percent of women (64 participants) who were 40 to 49. All but two of the 63 youngest women in the group of women diagnosed with melanoma reported tanning indoors.

Men were less likely to report indoor tanning use compared with women (44.3 percent vs. 78.2 percent), regardless of whether the men were diagnosed with melanoma or were comparison patients, which may explain the inconclusive findings for indoor tanning and melanoma among men.

Still, among men 30 to 39, about 41 percent were diagnosed as having melanoma on their trunk compared with 49 percent of men age 40 to 49, the study showed.

“Our results indicate that these efforts need to be accelerated and expanded beyond bans on minor access to indoor tanning to curb the melanoma epidemic, which seems likely to continue unabated especially among young women, unless exposure to indoor tanning is further restricted and reduced,” conclude study authors led by DeAnn Lazovich, Ph.D., of the University of Minnesota.

In a related editorial, Gery P. Guy, Jr., Ph.D., M.P.H., of the Centers for Disease Control and Prevention in Atlanta, and coauthors write that the new study  “highlights the need to address indoor tanning among young white women, among whom indoor tanning is most common.”