"The Middleplace" by Kelly Corrigan is about her dealing with breast cancer while her beloved father is dealing with Pancreatic cancer. It's very well written, humorous and I love the fact that she writes about thinking all of the horrible things you think about and would NEVER tell anyone about. It sort've sheds a light on the fact that it's okay to sometimes be angry about cancer, you don't always have to put up the brave soldier front. It's easy to read and doesn't try to give advice, so it provides inspiration without being preachy.
Prayers to your friends, they will need a lot of support through their illness.