It's a potentially life-threatening cancer, obviously, but treatment has advanced considerably so that there are many survivors. My BIL was diagnosed September 2005 and is now successfully in remission. It was a rough ride, though, for the first month or so.
It's not good that he's going into treatment with pneumonia. Prayers for his full recovery and that he's able to be back in his Senate seat by January.
Thank God your BIL is doing well.