Actor Gary Sinise said on Tuesday that his son, McCanna Anthony “Mac” Sinise, passed away last month at the age of 33 after battling a rare type of c͙a͙n͙c͙e͙r͙.

According to a heartfelt obituary written by Gary Sinise and published on his foundation’s website, McCanna “was smiling and filled with joy when he would hear (hospital staff) sharing how moved they were by the music” on his YouTube channel, which he had shared with them. “But the days became tougher, and on January 5th, with his family all around him, he let go. His battle with Chordoma had ended, and he was at peace.

The National Ca͙n͙c͙e͙r͙ Institute describes chordoma as a slow-growing poison of tissue found inside the spine. One in 1 million people worldwide are diagnosed with the disease each year.

“Our story is not unique,” Gary Sinise wrote. “No one escapes c͙a͙n͙c͙e͙r͙. It affects us all, as every one of us in this life knows someone, personally or otherwise, who has faced this awful disease.”

The obituary included photos of the father and son together on the road at the foundation’s Soaring Valor events, which honor WWII heroes, and the organization’s Invincible Spirit Festivals, where Sinise’s Lt. Dan Band, named after his well-known character in the film “Forrest Gump,” uplifts wounded personnel at military hospitals across the United States.

“Like any family experiencing such a loss, we are heartbroken and have been managing as best we can,” the elder Sinise wrote in the tribute. “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. Over the years I have met so many families of our fallen heroes. It’s heartbreaking, and it’s just damn hard.”