One look at Brian Alvarado and you wonder how he can still be alive. Especially when you get a glimpse at his pre-deployment photograph—a soldier in Marine service uniform, full-faced and ready for whatever war would dish out—and think, “is this really the same person?” Unfortunately, yes, Alvarado served two tours 10 years ago, and for a time he patrolled “hell,” which is what the guys called the open air burn pits on major U.S. military installations like Air Base Balad in Iraq. When he got home, according to his wife, he was diagnosed with Squamous Cell Carcinoma (throat cancer) and began...