Gary Sinise's son dead at 33: Forrest Gump star announces McCanna 'Mac' Sinise has passed away after battle with rare cancer Chordoma - as actor pays heartfelt tribute

Gary Sinise has shared the heartbreaking news that his son McCanna 'Mac' Sinise has died at the age of 33.

The 68-year-old Forrest Gump actor revealed that his son died on January 5 following a years-long battle with the rare spinal cancer Chordoma in a post shared to the Gary Sinise Foundation's website on Tuesday.

Mac had worked with the foundation and had supported his father's Lt. Dan Band as a fill-in drummer until repeated spinal surgeries and the advancement of his cancer in recent years forced him to step away.

'I am so blessed, fortunate, and proud to be his dad,' Sinise wrote in his moving obituary.

In a lengthy tribute to his son, Sinise recalled the twin tragedies of 2018, when his wife Moria was diagnosed with stage 3 breast cancer in June, before Mac received his chordoma diagnosis in August.

Gary Sinise has shared the heartbreaking news that his son Mac Sinise died on January 5 at the age of 33

Mac Sinise had been battling the rare spinal cancer chordoma in recent years, but he continued to work for his father's foundation until 2020

Mac's father Gary Sinise has had numerous acclaimed film and television roles in a decades-long career, but he is best known for playing Lt. Dan in the Tom Hanks–starring blockbuster Forrest Gump (pictured)

While Moira would eventually go into remission after successful surgery to remove lymph nodes, followed by chemotherapy and radiation treatments, her son was less fortunate. 

Sinise shared that his son underwent surgery in September 2018 to remove a tumor on his spine, followed by a second surgery in February 2019 to combat an infection.

The family got bad news in May of that year when a follow-up scan revealed that Mac's tumor had returned, and the cancer had spread.

Despite his worsening condition and difficult treatments, Sinise wrote that his son continued to come into the foundation's office regularly, and after he was unable to he continued to work behind the scenes.

The actor revealed that Mac's final project for the foundation was a podcast interview with father and son. 

Even after he stepped back to focus on his treatments and health, Mac turned to one of his passions: music.

Sinise wrote that his son could not longer play his main instruments, drums and piano, so he assumed 'music was a thing of the past.'

Mac had studied at the University of Southern California's Thorton School of Music, where he had begun work on an unfinished composition later titled Arctic Circles — 'inspired by the wintery nature shows he loved watching while lying in his hospital bed' — and he became determined to complete it before his time was up.

'The cancer had paralyzed him from the chest down, but he still had limited use of his right arm, and fingers on his left hand,' Sinise explained.

Mac could still select musical notes with a stylus strapped to his hand, and members of his dad's Lt. Dan Band collaborated with him to hone the piece.

Mac's friend from USC, the composer Oliver Schnee, also collaborated with him to make the final touches on the arrangement, before Mac paid for recording sessions.

After Mac's treatments for chordoma made it difficult to go to the Gary Sinise Foundation office, he continued working remotely. His final project was a 2020 podcast interview with his dad

Even as cancer left him paralyzed from the chest down, Mac — who went to music school at USC — returned to compose an unfinished piece he began writing while in school

Gary's buddies in his Lt. Dan Band helped Mac shape and arrange the piece, later titled Arctic Circles, and the composer Oliver Schnee (R) helped arrange it

But Sinise shared that his son's ambitions led the sessions to expand after he was urged to take up harmonic so that he could still play on the record.

'He did, and it was beautiful,' Sinise wrote.

Mac was then talked into recording a version of the traditional folk song Oh Shenandoah to feature his harmonic and to take advantage of the string section that had been contracted.

Sinise revealed that his son was inspired to record an entire album filled out with three more of his original compositions titled Resurrection & Revival, Resurrection & Revival, 'with a theme of bringing something that was old or unfinished back to life.'

Gary looked back fondly on their recording session on November 10, 2023, which would mark Mac's final birthday celebration.

'It was a very special day for him, and he asked me to play bass on one of the tunes, a cover of the old American folk song Red River Valley, with him playing harmonica,' Gary shared, adding that it was a song Mac's mother would sing to him when he was a child.

'That day was indeed a special day for the two of us,' he added.

But Sinise revealed that Mac was struggling to breathe was forced to go to the hospital on December 30, 2023, where he would remain to the end.

Mac lived long enough to complete his album, but he died on January 5, the same week that the album went to press, and Sinise revealed that his son was laid to rest on January 23.

'Like any family experiencing such a loss, we are heartbroken and have been managing as best we can,' Sinise wrote. 'As parents, it is so difficult losing a child.'

The actor, who has performed with his band at numerous events honoring members of the armed services over the years, extended his thoughts to others who had lost loved ones too.

The two worked together to record more of Mac's originals, as well as traditional songs, to flesh out an album titled Resurrection & Revival

Mac celebrated his 33rd birthday during his November 10 recording session on his expanded album, with Gary playing bass on one tune at his son's request

Gary revealed that Mac died the week that his album went to press. He was laid to rest on January 23

Sinise, who noted that Mac battled cancer for five-and-a-half years, wrote: '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,' he added.

Gary shared that his son was a cinephile, and he recalled that 'We always told him he reminded us of the soldier at the end of the extraordinary film 1917, running through the battlefield, bombs going off all around him, knocking him down one after the other, yet he keeps getting back up, refusing to quit and keeps running forward.'

'I am so blessed, fortunate, and proud to be his dad,' he added. 

Sinise emphasized that his family's story was 'not unique,' but he took inspiration from the many soldiers he had met over the years who had persevered with their own struggles. 

'I have learned from them and been inspired by them,' he wrote, adding, 'Knowing them gave me strength.'

The screen star continued: 'Our family is grateful for all those who have helped us, loved us, and supported us in this fight.' 

He concluded by addressing his late son directly.

'Thank you, Mac. You did it. Resurrection & Revival will live on. And so will you. In our hearts forever.'

'Thank you, Mac. You did it. Resurrection & Revival will live on. And so will you. In our hearts forever,' Sinise concluded his tribute. 'We will miss you and love you for eternity'

The Gary Sinise Foundation noted it would be updating the family on donations to the Chordoma Foundation or the Gary Sinise Foundation made in Mac's name; Sinise pictured in 2020

'We were blessed to have you in our lives as son, brother, and friend...and we will miss you and love you for eternity,' he wrote, before signing off as the 'Proud father of Mac Sinise.' 

The Gary Sinise Foundation noted that, though Gary and his family had not solicited gifts in Mac's memory, it would be updating the family on any donations to the Chordoma Foundation or the Gary Sinise Foundation made in his name.

'Mac was an inspiration to all of us here at the Gary Sinise Foundation. We are heartbroken and grieving the loss of such an incredible individual, colleague, and friend,' the organization wrote. 

Gary's tribute to Mac was followed by hundreds of notes and tributes in his memory.