Jason Overman has suffered a setback and will not be allowed to return to Utah Friday.

The 6-year-old Orem cancer patient developed a high fever Monday night and will be held at the UCLA Medical Center for more tests."They stayed up all night testing for different viruses, but they don't know what it is yet," Lorraine Hill, Jason's aunt, said Tuesday.

"They had to postpone Jason's trip until they can see what is causing the fever. The doctors told Jane (Jason's mother) to cancel the flight."

Jason has been a patient at the medical center since his Aug. 18 bone-marrow transplant. He suffers from neuroblastoma, a rare childhood cancer that attacks the nervous system.

After his condition was diagnosed in February, Utahns held fund-raisers and collected $192,000 to pay for the transplant - Jason's best hope of surviving his cancer.

Doctors had said Jason was doing better than average and last week said there was an 80 percent chance he would be released to Primary Children's Medical Center Friday.

"They told the family it was not for sure, but it is still a disappointment," Hill said.

The week before last, Jason had suffered badly from graph-vs.-host disease, Hill said.

"He had a 105-degree fever. We were very scared." Hill said the condition was under control as of last week.

About half of all marrow transplant patients suffer some degree of the rejection problem, Vicki Beck, UCLA Medical Center spokeswoman, said.

Jason's white blood-cell count had gone from zero following his radiation and transplant to 2,400 last week, Hill said. A normal count is 5,000 to 6,000, she said. White blood cells help the body fight infection. Hill had no information on Jason's current white count.

Even if Jason had been released to Primary Children's Medical Center, it would have been awhile before he could go home, Hill said.

"Jason would have to stay in Primary Children's until he could eat solid food - he hasn't in five weeks - and until he didn't need blood and platelet transfusions," Hill said. Such transfusions are a normal part of treatment for a bone-marrow transplant patient, Beck said. Platelets help the blood clot, she added.