Why are airplane pilots more likely to have skin cancer?

Question

I read on http://www.nytimes.com/2012/08/12/travel/faq-frequent-airline-questions.html?mcubz=1:

“Pilots do have a higher incidence of skin cancer,” said Dr. James M. Spencer, a member of the board of directors of the American Academy of Dermatology and an expert in skin cancer treatment and cosmetic surgery in St. Petersburg, Fla., referring to several studies about skin cancers among airline pilots.

Why exactly more pilots have skin cancer is not known (for instance it could be from cosmic radiation, changing circadian rhythms or from, say, spending a lot of time outdoors in the places they fly to). And to complicate matters, no one has done a scientific comparison of instances of skin cancer in frequent fliers versus non-frequent fliers, Dr. Spencer said.

The article was written in 2012. Since then, have we understood why airplane pilots are more likely to have skin cancer?

Answer 1

A recent study confirmed the increased risk of airline pilots of a certain type of skin cancer (basal cell carcinoma or "BCC").

Incidence of cancer among licenced commercial pilots flying North Atlantic routes
December 2017, Environmental Health 16(1):86

The risk is increased relative to the general population (who fly less frequently). Whilst there can be no proof, the authors hypothesize that "Basal cell carcinoma of skin is radiation-related cancer, and may be attributed to cosmic radiation."

This seems a very reasonable conclusion from the data available.