The number of children dying each year from cancer has reduced substantially since the 1950s, from 50-60 per year to fewer than 25, according to an analysis of childhood cancer trends.
The reduction in mortality largely reflects major improvements in diagnostic and treatment methods since the 1970s, according to a new report from the National Cancer Registry (NCR).
The greatest reduction in absolute numbers of deaths has been observed for leukaemia, which accounted for almost half of all childhood cancer deaths in the 1950s and 1960s. On average, fewer than 10 children per year have died from leukaemia in recent decades.
However, while mortality rates have improved, incidence rates have increased. The incidence rates of all cancers combined jumped by 27% between the periods 1994-2000 and 2008-2014.
Dr Paul Walsh, one of the authors of Trends in Childhood Cancers, said diagnostic improvements were likely to have played a part in increased incidence rates.
However, he said it was difficult to determine what caused childhood cancers. The association between tobacco and lung cancer in adults was clearcut, but with children, causes were not clear.
“There are a lot of unknowns in the whole area of what causes childhood cancer,” he said.
“You won’t get everyone to agree. Some might feel there are environmental factors or parental lifestyle factors, but with the majority of childhood cancers, the true cause is not known.”
On average, 137 cases of cancer were diagnosed per year among children under age 15 between 1994-2014. Average annual numbers rose from 117 per year during 1994-2000 to 163 per year during 2008-2014, partly reflecting increases in the childhood population. Since the 1950s, the number of cancer deaths among boys has been about 30-40% higher than among girls.
Of the three biggest cancer groups in children — leukaemias, lymphomas and tumours of the brain and central nervous system — only the latter showed any significant increase from 1999 to 2014, from 21 cases to 56.
Chemotherapy was the principal treatment for all childhood cancers combined, either alone or in combination with surgery and/or radiotherapy.
Five-year survival from childhood cancer as a whole has averaged 81% in the period 2004-2013. Of the 2,873 patients aged 0-14 diagnosed with cancer during 1994-2014, 2,289 were still alive at the end of 2014, and the ages of survivors ranged from 0 to almost 36 years, with the highest proportion (32%) diagnosed less than 5 years previously.
NCR director Prof Kerri Clough-Gorr said while childhood cancers are “thankfully rare, their impact on families is high”.
And while treatment improvements have led to marked reductions in mortality, Dr Clough-Gorr said further work is needed “to follow-up the growing numbers of survivors of childhood cancer, who may experience long-term health consequences related to their cancer treatment”.
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