Seattle Seahawks and Portland Trail Blazers owner Paul Allen revealed on Monday that the non-Hodgkin lymphoma he battled nearly a decade ago has returned.

Allen, 65, said he has already started treatment and that he plans to fight it aggressively. He also said that both he and his doctors are optimistic that he will beat the disease again, like he did when he was first diagnosed with the cancer in 2009.

“A lot has happened in medicine since I overcame this disease in 2009,” Allen said in a statement. “My doctors are optimistic that I will see good results from the latest therapies, as am I. I will continue to stay involved with Vulcan, the Allen Institutes, the Seahawks and Trail Blazers, as I have in the past. I have confidence in the leadership teams to manage their ongoing operations during my treatment.

“I am very grateful for the support I’ve received from my family and friends. And I’ve appreciated the support of everyone on the teams and in the broader community in the past, and count on that support now as I fight this challenge.”

Allen, who co-founded Microsoft with Bill Gates in 1975, purchased the Trail Blazers in 1988. He then bought the Seahawks before the 1997 season. The football franchise has since made three Super Bowl appearances, winning the title in 2014.

He is also part of the primary ownership group for the Seattle Sounders FC.

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