Gary Sinise, best known for his role as Lieutenant Dan in the 1994 movie "Forrest Gump," has just revealed that his only son, McCanna Anthony Sinise, has passed away after a five-and-a-half-year battle with cancer.

Sinise, 68, and his wife, Moira, 69, have three children together. McCanna, known as "Mac," was their middle child and was just 33 years old at the time of his passing. He was a graduate of the USC Thornton School of Music and a talented actor, composer, and drummer who often played with his dad's Lt. Dan Band. He was best known for his work in Mission to Mars (2000), Impostor (2001), and Luna & Lars (2015).

A message from Gary. https://t.co/Bb2ji85bSi pic.twitter.com/Jhlrx6q9W9

— Gary Sinise (@GarySinise) February 27, 2024

Mac was only 27 when he was diagnosed with a rare form of bone cancer known as in chordoma August 2018. Chordoma is a rare and malignant tumor that forms in the spine or in the base of the skull. Over time, it can put pressure on the spinal cord and brain, causing pain, weakness, or numbness in the back, arms, or legs. Depending on the location of the tumor, it can also cause vision problems, facial numbness, headaches, bladder problems, and bowel problems. Over time, it metastasizes to vital organs like the brain, lungs, or liver, and eventually results in death.

There is no known cure for chordoma. The most effective treatment for the disease is surgery to remove the tumor, but the surgery can also cause paralysis due to the tumor's proximity to the central nervous system. Even when treatment is successful, tumors often return later, requiring further treatment.

Photo: YouTube/Entertainment Tonight

Over the course of his cancer battle, Mac had five surgeries to treat his chordoma. The surgeries left him paralyzed from the chest down, but he did not stop fighting for his life.

Mac was a faithful Catholic, and his father reports that it was his trust in God that carried him through the roughest moments of his cancer journey.

Coincidentally, Moira had been diagnosed with stage III breast cancer a few months before Mac received his diagnosis. She went on to receive treatment, and her cancer went into remission. Her son, however, was not so lucky, despite his long and courageous fight.

Photo: YouTube/Entertainment Tonight

McCanna "Mac" Sinise passed away on January 5th, 2024, and was laid to rest on January 23rd. In February, Gary Sinise released a tribute to his son on social media to let his fans know about the sorrowful event.

"Like any family experiencing such a loss, we are heartbroken and have been managing as best we can," Sinise writes. "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.

"It’s heartbreaking, and it’s just damn hard. Our family’s cancer fight lasted for five-and-a-half years, and it became more and more challenging as time went on.

Hollywood actor Gary Sinise’s tribute to his son McCanna Sinise, a devout Catholic, who lost his life after a 5 1/2 year battle with a rare spinal cancer Chordoma

“Mac was a man who loved his Catholic faith, and there is no doubt that his strong faith sustained him through the… pic.twitter.com/Dxd34iJoVr

— Sachin Jose (@Sachinettiyil) February 28, 2024

"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."

The Sinise family hopes their story can help raise awareness for chordoma and that they can assist in furthering research to improve treatments or even discover a cure for this terrible disease so that others may not have to suffer this fate. But above all, Sinise writes, he is "blessed, fortunate, and proud" to be Mac’s father.

Photo: YouTube/Entertainment Tonight

"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. Even with one setback after another, he never stopped living and learning, creating, and giving, and loving."

Our hearts go out to the Sinise family during this very difficult time. Rest in peace, Mac.

https://www.youtube.com/watch?v=gPLFAWE5fTw