I did[1], and would be curious if anyone is familiar with the underlying study. How did they attempt to control for other factors? (I assume that they did, and am interested to know how)

Also do you have to get a sunburn for sun damage to increase the risk of skin cancers? My understanding was accumulated sun exposure was the issue.

[1] Lindqvist tracked the sunbathing habits of nearly 30,000 women in Sweden over 20 years. Originally, he was studying blood clots, which he found occurred less frequently in women who spent more time in the sun—and less frequently during the summer... decided to look at overall mortality rates, and the results were shocking. Over the 20 years of the study, sun avoiders were twice as likely to die as sun worshippers.