What is causing squamous cell carc?

Hello. I'm 24 year old female and I would like to find out more about one very serious skin condition.
Just recently my best friend told me that doctors suspect that her mother has developed some skin tumor called squamous cell carcinoma. Of course, she was devastated when I heard about it.
I really don’t know anything about it nether my friend.
All we know is that supposedly it is very aggressive and dangerous and that doctors will probably first have to find out is it spread to other organs!
Can someone tell me please- what is causing this Squamous cell carcinoma?

Hello. I'm very sorry about your friend’s mother and that’s why I will do everything I can to help!
It can be very difficult to say what exactly is causing this carcinoma but I can tell you that many think that chronic exposure to sunlight causes most cases of squamous cell carcinoma.
Of course, there are some other possible causes such as injury of the skin, chronic skin inflammation or medical conditions that suppress the immune system.
Luckily, it can be successfully treated and there are several options such as curettage and electrodessication, excisional surgery
radiation, cryosurgery and many others!