In early 2019, I was almost seven years out from my original melanoma diagnosis. I’d been living cancer-free since having surgery and radiation therapy during the spring of 2012, and I was looking forward to enjoying retirement with my wife.

Then, during a regular follow-up visit at MD Anderson, I got a crushing blow: the cancer had returned. Scans revealed I had three new tumors. Two were in my right lung. But the third was growing...