Seahawks owner and Microsoft co-founder Paul Allen announced Monday he is battling non-Hodgkin’s lymphoma again.

Allen, who was previously treated for the disease in 2009, wrote in a blog post on his website that he has begun treatment and he plans to fight it “aggressively.”

“A lot has happened in medicine since I overcame this disease in 2009,” Allen wrote. “My doctors are optimistic that I will see good results from the latest therapies, as am I.”

Non-Hodgkin’s lymphoma is a cancer that starts in the white blood cells

Allen said he will continue to stay involved with the Seahawks, the Allen Institutes, and his investment company Vulcan while undergoing treatment.