T-ALL is a form of childhood leukaemia
Scientists believe they have made an important breakthrough in attempts to treat a form of childhood leukaemia.
In mice tests, Australian researchers found that a cell, which plays a key role in T-cell acute lymphoblastic leukaemia, survives radiotherapy.
The Melbourne University team believes targeting this cell may help to stop this disease returning, but they warned much more research was needed.
UK experts said the findings may eventually lead to better care.
T-cell acute lymphoblastic leukaemia is a rare form of leukaemia which is most common in older children and adolescents, although adults can also be affected.
About a fifth of children suffer relapses after radiation therapy.
In the tests, the team found that 99% of cells in the thymus, a small organ in the upper chest which helps protect people from infections and as a result plays a key role in leukaemia, were killed by radiation.
But the Lmo2 gene was able to recover because of its stem-cell like properties, suggesting it could be responsible for the disease, the Science journal reported.
Lead researcher Dr Matthew McCormack said: "The cellular origins of this leukaemia are not well understood.
"Our discovery that these cells are similar to normal stem cells explains why they are capable of surviving for long periods.
"It also explains why they are remarkably resistant to treatment."
The team is now planning to focus on novel treatment capable of killing these cells, but warns it is still many years away from clinical trials.
Ken Campbell, of Leukaemia Research, said: "This is an interesting piece of research that increases our understanding of this small sub-set of childhood leukaemia patients.
"However, while the research could reduce relapse rates in the future for this group, it is likely that current treatment regimes will continue to be used."