Andrettis rally behind John's #checkitforAndretti campaign

John's son, Jarett, and cousin Michael held a news conference Thursday to speak on John's behalf and to advocate for people over 50 to have the screening that might have found John's cancer earlier.

"It felt like it went from colonoscopy to chemo in about two weeks," Jarrett said. "It may have been a little bit longer but it evolved very quickly, and I think that just shows the importance of getting a colonoscopy. Even couple weeks, a couple months could have made a huge difference."

Michael Andretti said the message is simple: Don't procrastinate.

"John hates the attention that he's getting on it because he's a very private person," he said. "But [John's] message is go out and get it done. Had he done it the year before he probably, everything would be all fine. It was only because he was procrastinating, because he knew he had to do it, but again, he was always too busy. So I think that's the whole message we're trying to put out here."

John Andretti released a statement on social media, thanking everyone for their support after WTHR-TV released a series of reports on John's cancer fight.

"I have been overwhelmed and humbled by everyone that has reached out to me by phone, text, social media or otherwise to send their prayers, well wishes and offer support," Andretti's statement begins. "My goal is to make people aware of the importance of screening through a colonoscopy. If you are 50 or your family has a history of colon cancer, waiting is not an option. You must be your own health care advocate. If you don't want to do it for yourself, do it for your family.

"Early detection is key and had I been screened sooner, my diagnosis would be much better. Bottom line is that colonoscopies save lives. PLEASE DO IT!

"Let us know when you decide to #checkitforAndretti."