Gutierrez signed for Newcastle in 2008 has scored 10 goals in 177 league appearances for the Magpies. He spent last season on loan at Norwich City.
Speaking to Argentine broadcaster TyC Sports, he said, "I detected a tumour in a testicle. When I confirmed the cancer, I went home crying,"
"I came here and I assumed the costs despite having a contract with Newcastle."
"Money is not important. What is important is health. I had to start chemotherapy."
Newcastle have not spoken officially about Gutierrez but he has received massive support from his team mates on social media, with former Newcastle players such as Joey Barton getting behind him.