Their survival rates for cancers such as leukaemia are much lower than in younger children, says a report in the Lancet Oncology.
The researchers
suggest differences in tumours, delays in diagnosis and treatment and a lack of
clinical trials for that age group are to blame.
Cancer Research UK
said it was crucial to find out what was going wrong.
The study analysed
data from 27 countries on nearly 57,000 childhood cancers and 312,000 cancers
in teenagers and young adults.
Overall, five-year
survival rates were higher in teenagers and young adults at 82% compared with
79% in children.
But those better
prospects were largely driven by the older age-group getting cancers with a
better prognosis.
The overall rate
concealed areas of concern where survival was "significantly worse" for
eight cancers commonly found in both age groups.
The five-year survival
rates for:
§
acute lymphoid leukaemias were 56% in teenagers and young adults
& 85.8% in children
§
acute myeloid leukaemias 50% in teenagers and young adults &
61% in children
§
Hodgkin's lymphoma 93% in teenagers and young adults & 95%
in children
§
non-Hodgkin's lymphoma 77% in teenagers and young adults &
83% in children
§
astrocytomas (a brain cancer) 46% in teenagers and young adults
& 62% in children
§
Ewing's sarcoma of bone 49% in teenagers and young adults &
67% in children
§
rhabdomyosarcoma (soft tissue tumours) 38% in teenagers and
young adults & 67% in children
§
osteosarcoma (bone cancer) 62% in teenagers and young adults
& 67% in children
Dr Annalisa Trama,
from The National Institute of Cancer in Milan, Italy said: "The good news
is that the number of children, adolescents and young adults surviving for at
least five years after diagnosis has risen steadily over time in Europe.
"However, we
found that adolescents and young adults still tend to die earlier than children
for several cancers common to these age groups, particularly blood
cancers."
Dr Alan Worsley, from
Cancer Research UK, said: "While it's great news that the number of
children, teenagers and young adults surviving cancer continues to improve,
it's also clear that for some cancers, survival in different age groups is
improving faster than in others.
"We need to find
out whether adolescents are faring worse because of how their cancer is managed
in the clinic or whether it's because the underlying biology is fundamentally
different at these ages.
"Answering these
questions is a big part of the reason why we've launched the Cancer Research UK
Kids and Teens campaign."
BBC
