The Survivor contestant battled Hodgkin's lymphoma in 2009 and eventually went into remission, but announced in November 2011 that the disease had returned.
Zohn has commented on his recovery in an interview with People, where he claimed that the chemotherapy drug SGN-35 has vastly improved his health.
"I'm responding very well to the drug. My tumours are reducing. It's not a 100% reduction, but my doctor gave me an A-minus so I'll take it," the reality star said.
The star is currently undergoing six chemotherapy treatments and will then receive a stem-cell transplant from one of his brothers.
Zohn previously joked that watching Keeping Up with the Kardashians helped him get through the draining cancer treatments.
He also praised girlfriend Jenna Morasca for standing by him through his battle with the disease.
Zohn won the third season of Survivor in 2002 and also partnered with Morasca for The Amazing Race.
> Survivor Ethan Zohn: 'Cancer not an issue for NYC marathon'