More children with cancer are surviving than in the past because of advances in treatment, but that doesn't mean the battle is over for all of them, the Canadian Cancer Society says.
For all childhood cancers combined, 82 per cent of Canadian kids who are diagnosed live at least five years, a jump of 11 per cent in the past 15 years, the society said Wednesday in releasing its 2008 national statistics on the disease.
"More children surviving cancer is welcome news," Heather Logan, the society's director of cancer control policy, said in a statement. "However, many survivors experience future health issues, called late effects, either as a result of the cancer or the treatment."
Ms. Logan said more research is critical so doctors learn how to better deal with these late-effect health problems, which afflict about two-thirds of children treated for cancer, a third of those seriously.
"Due to previous poor survival of children with cancer, there was limited opportunity to study survivors as they aged," she said. "As treatments have changed and improved, research is needed to understand what survivors of childhood cancer may face and what's needed to support them."
Pediatric oncologist Dr. Paul Grundy, chairman of the C17 Research Network for childhood cancer, said children who survive malignancies are at increased risk for physical and mental health issues, as well as development of secondary cancers.
Effects from the disease or treatment can appear months or even years later, with complications in hormone levels - leading, for example, to infertility or delayed puberty - and in metabolic function occurring most commonly.
The ability to think and reason may also be altered, causing difficulties in school. Such organs as the heart, lungs, stomach and intestines can also be affected, and children who have won the battle against one cancer may find themselves developing a second type of tumour later on.
Because certain cancers have a strong genetic underpinning, some survivors have concerns beyond their own health.
In the 1960s, Terry Hoddinott lost his sight to a rare eye childhood cancer called retinoblastoma, an inherited disease often passed from parent to child.
His Hoddinott's elder child, Riley, now 11, inherited the mutated gene that causes retinoblastoma. But because of early diagnosis and treatment, doctors were able to save his sight in one eye.
Riley's sister, Katie, two years younger, was diagnosed with the disease before she was born and treated early, leaving her sight intact.
"Little was known about retinoblastoma when I was a child," Mr. Hoddinott, of London, Ont., said. "But in the 1980s, researchers began closing in on ways to fight this cancer. Research helped save three of my children's four eyes."
Dr. Grundy said collaborative clinical trials throughout North America have been the key to progress against childhood cancer, which each year is diagnosed in about 850 Canadian kids up to age 14, killing about 135 of them.
"Pooling resources ensures enough children participate in trials to achieve effective results in a timely way," he said. Nearly 80 per cent of children with cancer are either enrolled in a clinical trial or treated according to a protocol established by a clinical trial.
Other childhood cancer statistics released Wednesday:
• Leukemia is the most common cancer affecting children, accounting for 33 per cent of new cases and 27 per cent of deaths each year.
• Cancers of the central nervous system are the second most common (20 per cent of new cases, 30 per cent of deaths) and lymphomas are third (12 per cent of new cases, five per cent of deaths).
• Rates of new cancers are highest among children up to age four; overall, cancer occurs more commonly in boys than girls.
• Since 1985, the number of new cancer cases overall has remained relatively stable, varying from 144 per million children to 159 cases.
• Since 1985, the rate of childhood cancer deaths has been halved, to 20 deaths per million children.