Mara said in a statement released by the team that he has been following a treatment plan recommended by doctors. He did not disclose what form of cancer he has and asked for privacy on the matter.
"I'm feeling strong and optimistic, and I'm committed to seeing this through to a positive outcome," Mara said. "I'm fortunate to be surrounded by incredible support - personally, professionally and medically."
Mara, 70, added that he expects to remain active with the team as president and CEO while being treated. He was at the Giants' practice facility in East Rutherford, New Jersey, last week when coach Brian Daboll formally named rookie Jaxson Dart the starting quarterback.
The Mara family has owned the storied NFL franchise since its founding in 1925.
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