Hamza Iskandar has only been fighting gastroesophageal cancer for the past six months, but he was born a fighter. 

As a result of his congenital heart disease, the 21-year-old from Jeddah, Saudi Arabia, learned to have incredible strength in times of adversity long before his cancer diagnosis.

He had open heart surgery at age six, a second at age seven and a third at twelve. He now has a mechanical valve in his...