Hope for Recurrent Cancer

If my dad is only stage 2, and after the major surgery to remove the esophagus and use the stomach to make a new esophagus and then they found a recurrent tumor where the two organs tied together. He had trouble swallowing, but after the first chemo round, the tumor apparently shrunk down because he could swallow. Is he stage IV because it's recurrent? I see so many hopeful stages that are extreme. Why do I feel like I'm on borrowed time with me dad.