The 47-year-old Schilling divulged the news in a statement released through his employer, Bristol-based ESPN. It did not indicate what type of cancer Schilling has, when he was diagnosed or what his prognosis might be.
"With my incredibly talented medical team I'm ready to try and win another big game," said Schilling, who retired in 2009 after 20 years in the major leagues.
"I've been so very blessed and I feel grateful for what God has allowed my family to have and experience, and I'll embrace this fight just like the rest of them, with resolute faith and head on."
ESPN spokesman Mike Soltys said Schilling is taking a leave of absence. He recently signed a multiyear contract extension with the network and was to be part of the "Sunday Night Baseball" broadcast team, as well as contribute to the network's studio coverage, including its spring training coverage, Soltys said.
"Our thoughts are with Curt and his family during this challenging time," the Bristol-based network said in a statement. "His ESPN teammates wish him continued strength in his cancer fight and we look forward to welcoming him back to our baseball coverage whenever he's ready".
Schilling played for five teams during his Major League career. He won three world championships, with the Arizona Diamondbacks (2001) and Boston Red Sox (2004, 2007), sharing the World Series MVP award with teammate Randy Johnson in 2001. He pitched for the Astros in 1991.
He won 216 games and struck out 3,116 batters during his career, but is perhaps best known for pitching in the 2004 ALCS and World Series after having stitches to mend an ankle injury. His bloody sock was later put on display in Cooperstown.
Schilling has been in the news recently after the failure of 38 Studios, a video game company he owned in Rhode Island, with the help of a $75 million state loan guarantee. The company went bankrupt last year, leaving Rhode Island taxpayers on the hook to pay back tens of millions of dollars.
Schilling said he invested and lost as much as $50 million.
This is not the first time he and his family have battled health issues.
Schilling recently revealed he suffered a heart attack in November 2011. His wife, Shonda, successfully battled melanoma in 2001.
His daughter, Gabby, took to Twitter on Wednesday to ask for prayers for her father.
"So i guess the word is out, if everyone could just keep my dad and family in their prayers it would mean a lot!" she wrote.
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