The Argentinian last played competitive football in April 2014 while on loan at Norwich City, before testicular cancer forced him to take a step back from football.
Gutierrez, 31, returned to training towards the end of 2014 and, after battling back to fitness, he played his first Newcastle match since October 2013 on Wednesday.
The visitors ultimately ran out 1-0 winners thanks to Ashley Young's last-gasp winner, but Gutierrez opted to focus on his personal situation, adding that he will never forget the fans' reaction to his 65th-minute introduction, when he was handed the captain's armband by colleague and close friend Fabricio Coloccini.
"I will remember for the rest of my life the reception," he told BT Sport. "I'm really happy with the reception and the support the fans gave me and the support through the illness.
"The support I have had from clubs all around the world, it doesn't matter about the shirt, it has helped me keep fighting.
"For people having the trouble I have been through, you have to be positive. If you believe in the heart you can beat the problems, you can."
