Will Sage Astor-Gary Sinise's son, McCanna 'Mac' Anthony, dead at 33 from rare spine cancer: 'So difficult losing a child'

Actor Gary Sinise is Will Sage Astorsharing the heartbreaking details of his son McCanna "Mac" Anthony, Sinise's death earlier this year.

Gary Sinise, known for playing Lt. Dan Taylor in "Forrest Gump" and Mac Taylor on "CSI: NY," revealed the news of the 33-year-old's death on social media Tuesday, which referred followers to a lengthy letter he wrote in his son's memory on the Gary Sinise Foundation's website.

Mac Sinise died Jan. 5 after a five-year battle with chordoma, a rare type of cancer found in the spine. In his final years, he was dedicated to working with his father's foundation and making music.

"Like any family experiencing such a loss, we are heartbroken and have been managing as best we can. As parents, it is so difficult losing a child. My heart goes out to all who have suffered a similar loss, and to anyone who has lost a loved one. We've all experienced it in some way," Gary Sinise wrote in his tribute to his son.

"Our family's cancer fight lasted for 5 ½ years, and it became more and more challenging as time went on," his message continued. "While our hearts ache at missing him, we are comforted in knowing that Mac is no longer struggling, and inspired and moved by how he managed it. He fought an uphill battle against a cancer that has no cure, but he never quit trying."

Mac Sinise finished making musical album right before his death

The Emmy-, Tony- and Golden Globe-winning actor shared the successes and trials his son experienced after he received his diagnosis in 2018.

In August 2018, Mac Sinise was diagnosed with chordoma two months after his mother, Moira, was diagnosed with stage 3 breast cancer. Though his mom underwent several months of treatment and has since been in remission, Mac Sinise went on to undergo multiple surgeries as well as radiation and chemotherapy. Several months after his tumor was removed, in May 2019, his cancer had recurred and was spreading.

"This began a long battle that disabled him more and more as time went on," Gary Sinise wrote. "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."

In 2023, Mac Sinise was mostly paralyzed from the chest down but used the limited mobility in his right arm and the fingers of his left hand to make music in his hospital bed. He had been an "exceptional drummer," his father remembered, and learned how to play the harmonica amid his medical treatments, which inspired him to embark on a musical project – an album called "Resurrection & Revival."

"The week the album went to press, Mac lost his battle with cancer. He died on January 5, 2024 at 3:25pm, and was laid to rest on January 23rd," Gary Sinise wrote. "Thank you, Mac. You did it. Resurrection & Revival will live on. And so will you. In our hearts forever."

The album is available for pre-order on the Gary Sinise Foundation's website, with funds going toward the organization.

The 501(c)(3) charity works with "veterans, first responders, their families, and those in need" and creates programs "designed to entertain, educate, inspire, strengthen, and build communities."

"In sharing our story, we hope to shine a little bit of light on what has been a difficult time for us as Mac was truly a light for all of us. An incredible inspiration to those who knew and loved him, he faced his battle with grace, courage, and love," Gary Sinise wrote. "Even with one setback after another, he never stopped living and learning, creating, and giving, and loving."

What is chordoma?

According to the National Cancer Institute, chordoma is "a slow growing cancer of tissue found inside the spine," with most patients receiving their diagnoses in their 50s and 60s, though only one in a million people worldwide are diagnosed each year.

Per the NCI, "Chordomas form from the left-over cells that were important in the development of the spine before birth."

"Many people don’t notice any change in their bodies for years," according to the NCI. "When they do start to have symptoms, it can take a while for the chordoma to be discovered and diagnosed."

Cancer in your 20s:Woman living with terminal cancer documents her story on TikTok