Childhood leukemia and socioeconomic status in Canada

Vancouver, B.C. June 23, 2005. A BC Cancer Agency study analyzing more than 5,200 cases of childhood leukemia in Canada shows children living in the country's poorest neighbourhoods have a lower risk of developing the disease compared with children in the richest neighbourhoods. The results appear in the July issue of the journal Epidemiology.

It is the largest Canadian study to look at socioeconomic status as a factor in childhood leukemia risk. The study found children in the poorest neighbourhoods had a 13 percent reduction in risk of leukemia compared with children in the richest neighbourhoods. For acute lymphoid leukemia (the most common sub-type of childhood leukemia) children in the poorest neighbourhoods had a 14 percent reduction in risk.

Researchers accessed data from all 10 provincial cancer registries, linking the information with Statistics Canada Census data on neighbourhood incomes. All cases of childhood leukemia (ages birth to 19) diagnosed from 1985 to 2001 were identified.

"This study doesn't tell us why the poorest group has a lower risk," says Dr. Marilyn Borugian, principal investigator for the study." It could be that early exposure to viruses - which might be more prevalent in neighbourhoods with lower incomes and more crowded living conditions - may provide some protection."

"Further research is required to look at the role of specific agents or factors that might be the cause."

The BC Cancer Agency researchers are currently conducting similar studies on whether there is a socioeconomic link with other common childhood cancer sites such as brain cancer, bone cancer, and Hodgkin's lymphoma.

The study was funded by the Electric Power Research Institute. Study co-authors include John Spinelli, Mary McBride and Zenaida Abanto of the BC Cancer Agency; Gabor Mezei, Electric Power Research Institute; and Russell Wilkins, Statistics Canada.

Each year, an average of 1,285 children are diagnosed with cancer in Canada, and 227 die from the disease. Leukemia accounts for 26 percent of all new cancer cases, and remains the most common of childhood cancers. Acute lymphoid leukemia accounts for about 250 cases, and 28 deaths a year in Canada.

While dramatic improvements have been made in treating childhood leukemia, for the most part, the causes of childhood leukemia are not well understood.

The BC Cancer Agency, a part of the Provincial Health Services Authority, is committed to reducing the incidence of cancer, reducing the mortality from cancer, and improving the quality of life of those living with cancer. It provides a comprehensive cancer control program for the people of British Columbia by working with community partners to deliver a range of oncology services, including prevention, early detection, diagnosis and treatment, research, education, supportive care, rehabilitation and palliative care. The BC Cancer Foundation supports research and care at the BC Cancer Agency and BC Cancer Research Centre.

Research Team

• John Spinelli
• Mary McBride
• Zenaida Abanto