A member of the Broncos coaching staff has stepped away from work to fight an aggressive form of cancer.

Denver passing game specialist Zack Grossi, who is in his third year on the Broncos’ staff, started chemotherapy this week after he was discovered to have a yolk sac tumor in his chest.

Grossi, 35, said in a message shared with the team’s website that he first started feeling off a few months ago.

From his message:

“For the last three months, I felt a little bit off, and recently, I began to have trouble breathing. Last week, I went to the Broncos’ medical staff, and they told me we needed to run several tests. I underwent bloodwork and a scan, and that’s when they found the tumor in my chest cavity.

“Officially, I have been diagnosed with a Yolk Sac Tumor.

“The diagnosis is scary, but the good news is it’s highly treatable. I began chemotherapy this week, and after a few more months of chemo, I’ll have surgery to remove the remaining tumor. My approach isn’t so different than getting ready for a game. I’ll stay the course, keep working and keep grinding. ‘Day by day’ is my motto. I have marching orders from my doctors, and I’m trusting the process.”

Grossi works primarily with Denver’s wide receivers and has for the past three seasons. Before joining the Broncos staff in 2022, he worked in Louisiana at the college level at Southern University and A&M College and in 2019 as Hampton University’s quarterbacks coach. Grossi first worked in the NFL in 2014 as a scouting assistant for Tampa Bay and was with the Buccaneers in various capacities through the 2018 season.

Head coach Sean Payton in a statement said, “Our unwavering support is with Zack and his family as he takes some time away to focus on his health. Knowing what Zack is all about and talking with him since his diagnosis, I have no doubt he will Fight Like A Bronco. We’ll be with him every step of the way and can’t wait to welcome him back to our staff.”

Grossi said he doesn’t want to estimate when he might return to work, “but I can’t wait to get back to doing what I love.”

“After I was diagnosed, the outreach from (Broncos CEO) Greg Penner, Carrie Walton Penner and the Broncos was immediate,” he wrote. “The night of my scan, Greg texted me to tell me I had his and Carrie’s full support. From Sean Payton to (general manager) George Paton to (vice president of player health and performance) Beau Lowery, (athletic trainer) Vince Garcia, Dr. Steven Geraghty and Dr. Andrea Holland, the Broncos’ support was truly overwhelming. They have gone above and beyond, and it’s hard to put into words what it means to me.

“Everything they’ve done for me, my wife, Jacqueline, and my daughter, Sophia, has been first class. That includes the Broncos Family Network, which has been incredible to my wife. There’s times — because of all the support — when I feel like the luckiest man in the world.”

Reynolds, Wattenberg go on IR >> Starting wide receiver Josh Reynolds (hand) and center Luke Wattenberg (ankle) were put on injured reserve Saturday. Neither is a major surprise, but both will test Denver’s depth.

The Post reported Friday that Reynolds needed minor surgery on his finger after an injury late in Sunday’s win against Las Vegas.

Wattenberg appeared to suffer a substantial injury after Nix’s fourth-quarter sneak for a touchdown. He was able to get off the field on his own but not before several other offensive linemen gathered around him while he was on the ground.

The earliest either can return is Week 10 at Kansas City.

Alex Forsyth, a second-year player and former college teammate of Nix’s at Oregon, will take over at center now for at least the next month.

To replace them on the 53-man roster, the Broncos are activating rookie running back Audric Estime off of injured reserve and signing safety Tanner McCalister from the practice squad.

OL reinforcements >> With Wattenberg on injured reserve and right tackle Alex Palczewski (ankle) out for Sunday’s game against the Chargers, Denver promoted guard Calvin Throckmorton and tackle Cam Fleming from the practice squad for Sunday’s game.

Fleming was just signed earlier this week but started one game for Denver last year and 15 in 2022.

Throckmorton has been with the team since the summer and has been on the practice squad since the end of the preseason.

Expensive third quarter >> Three Broncos incurred fines in the third quarter of Sunday’s win against the Raiders: DL John Franklin Myers ($14,069, unsportsmanlike conduct), FB Mike Burton ($7,653, blind-side block), DL Malcolm Roach ($11,255, late hit).