He told a news briefing today (Monday 1 March) at the Teenage Cancer Trust's Third International Conference on Adolescent Oncology, that survival among younger and older people had now surpassed that of teens and young adults.

"Adolescents and young adults have fallen behind orphaned in the world of cancer care delivery," he said.

The failure to improve survival among 15 to 29-year-olds over the last quarter of a century was striking, especially relative to the 39-46% increase in 5-year survival of children and young adolescents. "The reasons vary from country to country, but they are more similar than different."

Professor Bleyer, who is Director of the Community Clinical Oncology Programme at the University of Texas MD Anderson Cancer Centre in Houston, outlined some of the causes:

Psychological and social factors meant patients may be at a higher risk for delayed diagnosis and this may impact on survival. One study found that for all solid tumours except Hodgkin's disease, as age increased lag time increased.

Adolescents and young adults feel they are invincible and tended to give poor information, especially to doctors untrained in reading between the lines. " Some of the most advanced diseases occur in adolescents. We have older adolescents with extraordinarily large masses of the breast, testes, abdomen, pelvis and extremities that they've harboured for months because they were too embarrassed to bring the problem to anyone's attention," he said.