In August 2013, I completed my first Ironman triathlon -- a 2.4-mile swim followed by a 112-mile bike ride and a 26-mile run. 

Only 16 months earlier, I’d been diagnosed with stage III kidney cancer at MD Anderson. I’d traveled 1,141 miles from my home in the Cayman Islands to MD Anderson, where I underwent a partial nephrectomy. 

My cancer was found by chance. After visiting my local doctor for two hernias, an...