Doctors at a children's hospital in Ottawa are meeting today to review why a four-year-old boy was given a fatal overdose of an experimental cancer drug.

Nine senior staff at the Children's Hospital of Eastern Ontario will look at the circumstances that led to Ryan Lucio's death in late September.

The boy had been diagnosed in January with a severe case of neuroblastoma, a rare cancer, and his chances of survival were estimated at 20 to 35 per cent.

His doctors tried conventional treatments -- chemotherapy, a stem-cell transplant and radiation therapy -- and finally signed him up for a clinical trial with a drug that should have stimulated his immune system to attack cancerous cells.

"He went through the whole gamut of traditional treatment approaches," said hospital chief of staff Simon Davidson.

But seven days after Ryan and another child began receiving the colourless liquid, Interleukin II, doctors realized they had miscalculated the dosages.

The instructions that accompany the drug packages usually tell doctors to calculate the dosages according to the patient's weight. But for the clinical trial, the dosages were to be calculated using the patient's surface area.

The wrong numbers were transferred onto a sheaf of printed medication orders and escaped the notice of 15 professionals -- doctors, nurses, pharmacists and others -- who checked them.

Ryan died three days later, on Sept. 30. The other child survived.

Deaths due to medication error are a tragically common occurrence in Canadian hospitals, experts say; what is unusual about this case was the response of the Ottawa hospital.

Even before the boy died, the hospital alerted both families and the other institutions involved in the clinical trial across North America. On Monday, it issued a detailed statement, explaining what happened and promising to make public the results of its investigation.

"I have to commend and congratulate the hospital for sharing this data," said David U, president of the Institute for Safe Medication Practices Canada.

Medical mistakes aren't usually made public. Studies have found that errors account for about 44,000 to 98,000 deaths a year in the U.S. health system, meaning that between 5,000 and 10,000 people could be dying by accident each year in the Canadian system. The first Canadian study of the problem is expected to be completed in 2004.

In the meantime, many hospital officials are trying to break the culture of silence at their institutions by reporting and investigating accidents without blaming staff.

"One of the things we really want to do is to look at the root cause," said Susan Richardson, the Ottawa hospital's vice-president of patient services.

A funeral was held for Ryan near his home in Sault Ste. Marie, Ont., on Saturday. His family declined to speak with the media.