I'm so sorry for your friend. I know it is scary, but as you know, there is always hope.
I can tell you from personal experience in my own family that thyroid cancer is often very treatable with excellent results. Of course, as with prostate cancer, this depends on the type of cancer and the treatment chosen.
I know my wife would be happy to have an e-mail exchange with your friend to help provide some information and support. You may contact me with the e-mail in my profile if you wish.
All the best,