They can be the first step on the road to squamous cell carcinoma, and some experts even consider them the earliest form of SCC. From two to ten percent of untreated actinic keratoses (AKs) advance to squamous cell carcinoma, sometimes with two years, according to different studies.
Obi-Wan Ben Kenobi is a fictional character in the Star Wars universe, portrayed by Alec Guinness and Ewan McGregor in the films. In the original trilogy, he is a mentor to Luke Skywalker, whom he introduces to the ways of the Jedi. In the prequel trilogy, he is a master and friend to Anakin Skywalker.
Albus Dumbledore was played by Richard Harris in the first two Harry Potter movies. Michael Gambon played Dumbledore in the remainder of the movies. Ian McKellan played Gandalf in the Lord of the Rings. So, no, they weren't the same actor. I've heard that McKellan was offered the role of Albus Dumbledore after the death of Harris.