INDIANAPOLIS — It took Chuck Pagano less than nine months to instill his fighter’s mentality and hopeful spirit in the Indianapolis Colts.
He will need both to survive the biggest battle of his life — leukemia.
In a somber news conference Monday, the Colts announced that their new coach had been hospitalized for cancer treatment and probably would not return to full coaching duties this season. He will be replaced on an interim basis by offensive coordinator Bruce Arians.
‘‘He will do fine,’’ Arians said, his voice cracking as he recalled his own fight with prostate cancer in 2007. ‘‘I know him. He’s a fighter. As a cancer survivor myself, I know that these first few days are really hard on you but as he and I talked yesterday, it’s just a matter of time.’’
The news hit hard in all corners of the team complex.
Team owner Jim Irsay, who began his career as a Colts ball boy in the early 1970s, said the only comparison he could come up with was Vince Lombardi’s cancer diagnosis during the summer of 1970.
New general manager Ryan Grigson read stoically from his prepared notes, and Arians struggled to hold back tears.
“When I first heard about it, my heart dropped,’’ cornerback Jerraud Powers said. ‘‘You think about your family members or someone that’s actually been affected by it. But Chuck will beat this thing, there’s no doubt in my mind.”
The news trickled out publicly just as players and assistant coaches were returning to the team complex after the Colts’ bye week and one day before Pagano’s 52d birthday.
He was admitted to an Indianapolis hospital last Wednesday to begin treatments for acute promyelocytic leukemia, an illness in which the bone marrow produces abnormal white blood cells that interfere with healthy blood cells. Symptoms can include weakness, weight loss, and easy bruising or bleeding.
Pagano’s physician, Larry Cripe, said the coach will be treated with chemotherapy and drugs — a process that usually requires patients to spend 4-5 weeks in the hospital. Irsay said he expected Pagano to stay a bit longer, 6-8 weeks.
With most players and coaches out of town over the weekend, Pagano, a father of three girls, notified Arians in a heartbreaking call Sunday.
‘‘When Chuck called me yesterday, I was floored. I was down south at my home in Georgia and he was chatting like he always chats, and then he drops the news on me,’’ Arians said. “My first reaction was how is everything, how’s Tina, how’s the girls, is everything going to be all right?’’
Grigson and Arians were still trying to figure out how the coaching duties will be handled during Pagano’s absence, and the focus was increasingly on things of far greater significance than just football.
‘‘I think short of death, this is the worst type of news you want to hear,’’ rookie quarterback Andrew Luck said. ‘‘We’ll do everything we can in honor of what Coach Pagano is going through in honor of his fight, which is much more important than this kid’s game we play.’’