DENVER (KDVR) — The death of former Broncos running back Ronnie Hillman has left all of Broncos Country heartbroken.

He’s the second former Broncos player from that historic Super Bowl 50 team to die in about a year. The other is Demaryius Thomas.

Hillman’s family says the 31-year-old died from renal medullary carcinoma, which is a cancer of the kidneys.

Teammate Ryan Harris: ‘We don’t win without Ronnie Hillman’

FOX31 spoke with a former teammate about how this loss has hit Broncos Country especially hard. Short is also getting some expert insight on the type of cancer that took Hillman’s life.

“For this Super Bowl championship team, the Super Bowl 50 team, we’ve dealt with a lot of loss now in the last two years,” Ryan Harris said. Last year’s loss of Thomas still lingers for the former lineman. He was also Hillman’s teammate.

“There were a lot of us who also know that we don’t win without Ronnie Hillman,” Harris added.

Hillman’s cancer often linked to sickle cell trait

Questions have run rampant surrounding renal medullary carcinoma, which is a rare kidney cancer, according to Dr. Rachelle Nuss. She’s the associate director of the Colorado Sickle Cell Treatment and Research Center on the University of Colorado Anschutz Medical Campus.

“It’s less likely than getting struck by lightning,” Nuss explained, saying that “80% or more of the time, it occurs in people who have sickle cell trait. The rest of the time, it may occur in someone who has sickle cell disease.”

That disease is an inherited blood disorder, according to the American Society of Hematology. Healthy red blood cells are flexible and can move through the smallest blood vessels. In sickle cell disease, the red blood cells are rigid and shaped like a “C,” or sickle.

“It is very unlikely (Hillman) had sickle cell anemia for the stamina that is required to be an NFL player,” Nuss said. “If he had anything, it would more likely be sickle cell trait.”

FOX31 does not know if he had sickle cell trait or the disease, but we do know he was diagnosed with the rare, incurable cancer in August and died four months later.

“Ronnie Hillman was told he was too young and too small to play in the NFL when he entered the NFL Draft,” Harris told FOX31. “He finished five years and a Super Bowl champion. That type of dedication is capable within all of us.”

This cancer has occurred in children as well, some as young as 5 years old.

FOX31 asked Dr. Nuss about the survival rate for those who end up with the rare type of kidney cancer. She said, “virtually nothing.” She added: “When this cancer is detected, by the time it’s detected, it has spread, and we don’t have any effective chemotherapy radiation, any way to treat it.”

Signs and symptoms of sickle cell include anemia (paleness), dark urine, yellow eyes and swelling of feet and hands. Some people suffer from frequent pain episodes too. A simple blood test can determine if you have it, but like the rare kidney cancer Hillman had, sickle cell is incurable.