If the Pasco County Sheriff’s Office corporal hadn’t broken his back, he said, doctors probably wouldn’t have found the cancer.

“It was a blessing,” the 49-year-old called the car crash.

It wasn’t the only blessing Derner would receive. This week, a dozen sheriff’s deputies helped pack up boxes in Derner’s third-floor walk-up apartment, readying him for a move to a more accessible single-story house on his friend’s land.

On Wednesday, a moving company donated its time to finish the job, taking the boxes and all of Derner’s furniture to his new home, owned by friend and former Philadelphia Phillies pitcher Scott Mathieson.

Derner was supposed to be a student resource officer this year at Crews Lake Middle School in Shady Hills. But a few weeks before school started, the 25-year veteran was giving a driving lesson to a Sheriff’s Office volunteer. The driver accidentally stepped on the gas pedal instead of the brake, losing control and crashing.

The driver was uninjured, but Derner, a former Navy corpsman, suffered a crushed vertebra, pushing pieces of broken bone against his spinal cord. He couldn’t feel or move his legs after the crash, he said.

Things only got worse. At the hospital, doctors discovered a mass on one of his lungs.

“The oncologist told me it’d probably be about six months before I started showing symptoms,” Derner said. “Usually, with someone at my age, by the time you present with the symptoms, it’s too late for them to do anything.”

Two incredibly invasive surgeries later, Derner was cancer-free and walking around.

“The neurosurgeons, to me they’re miracle workers,” Derner said Wednesday on his balcony waiting for the movers to arrive. “They work for God, for sure. They were able to get me to walk again and to feel my legs right after my surgery.”

But more bad news was on the horizon. Last month, Derner learned he had a staph infection, and doctors opened him back up along his lung surgery scar — from the back of his neck to under his right arm — and removed a portion of an infected rib.

“Three trips to the ICU in six months helps you realize just how fragile life is,” he said.

All the trauma took a toll on his two kids, Derner said. Derner’s father died of lung cancer just one month before he learned of his own, and it rattled his 14-year-old daughter, he said.

Derner hopes to return to the Sheriff’s Office part time in May. He said he draws inspiration during his recovery from his colleagues and students, who send him words of encouragement — and his dog, a 3-year-old boxer named Braxton, with whom Derner was reunited on Tuesday after a month apart.

“It makes you realize we’re all in this world to make a difference, and you can,” he said.