I was hoping I had put cancer behind me. I knew I would always have to watch for any signs of recurrence, travel to Houston regularly for checkups and even have a biopsy if anything suspicious popped up.

But in April 2015, I was back at square one. I’d noticed a suspicious looking, cyst-like spot on the left side of my tongue a few weeks earlier, so during my checkup at MD Anderson, I discussed it with my doctor, Eduardo Diaz,...