Actor Gary Sinise has announced that his son, McCanna Anthony "Mac" Sinise, passed away on January 5 at age 33 after a lengthy cancer battle.

Mac was diagnosed with the rare cancer chordoma in August 2018 and became increasingly disabled over time, his father explained in a tribute posted on the Gary Sinise Foundation website. Sinise noted that his son had worked for the Foundation but eventually had to give that work up.

The organization's mission is to "serve our nation by honoring our defenders, veterans, first responders, their families, and those in need." For example, one of the group's initiatives is to "build 100% mortgage-free specially adapted smart homes for our most severely wounded heroes."

"With Mac, after surgery to remove the initial tumor in September of 2018, and another spine procedure in February 2019 to clear what looked like an infection, unfortunately a follow up scan in May of 2019 would show that his Chordoma had come back and was spreading. This began a long battle that disabled him more and more as time went on. The cancer fight was getting harder, but throughout most of 2019 he was still able to come to the GSF office, until a third spine surgery in November of that year," Sinise wrote.

"While in recovery at home, he was still eager to contribute to the Foundation and he was excited to launch our Gary Sinise Foundation podcast. He was just getting started, completing two interviews, the first with our Gary Sinise Foundation video producer Kip Perry, and the second with yours truly. In January of 2020, the day before he went in for his 4th spine surgery, Mac and I sat down together for his GSF podcast interview with me. This would finish his work with Gary Sinise Foundation. That year, he knew he had to step away to fight his battle. He would have to focus full-time on recovery and rehab, as there would be a fifth spine surgery in June, along with radiation and continuing chemotherapy," Sinise continued.

But despite his physical limitations, Mac, who had graduated from the USC Thornton School of Music, worked on creating music during his cancer battle, including by completing "Arctic Circles," an unfinished composition that he had started in college. The piece was recorded last year.

"Now, 10 years later, I found a way to write music again in my hospital bed. In addition to getting back in touch with a producer friend from college, Oliver Schnee, I recovered my old piece and I decided to go for it!" part of the description section of the YouTube video for the piece reads on the Mac Sinise YouTube channel. "Time is precious and I want to take advantage of the times that I feel strong. The result has been incredible collaborations with members of the Lt Dan Band and my buddy Oliver Schnee to finally finish writing and recording 'Arctic Circles'."

"His music videos can be seen in their entirety on Mac Sinise YouTube. Included with the video of 'Arctic Circles' is a special text message from Mac that I found on his phone after his death. He intended to post it as he was so happy to share this piece of music with you all," Gary Sinise wrote. "The album, Mac Sinise: Resurrection and Revival, will be finished and available soon."

"He gave his family and friends so much during his 33 years, and he accomplished great things in those final months. With a glorious teaming of two old pals from college, his vision for this beautiful music was realized," Gary Sinise wrote. "Mac's inspiring parting gift to us. Thank you, Mac. You did it. Resurrection & Revival will live on. And so will you. In our hearts forever."

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