23 January 2023

New research on twins has shed light on the development of childhood acute lymphoblastic leukaemia.

The study, led by a team at the Institute of Cancer Research (ICR) in London, confirms earlier research that childhood ALL originates in the womb, but events after birth determine whether or not leukaemia develops.

Writing in Leukaemia, Professor Sir Mel Greaves and his team followed pairs of identical twins for up to 15 years. It was already known that if one twin develops leukaemia, the other has an increased risk of also developing the disease.

The researchers say this is because two changes are needed to determine whether or not a child develops leukaemia: one before birth, which both children will have if they have shared a blood supply, and one after.

They believe this second ‘hit’ is caused by an event such as an infection and may only affect one sibling.

Prof Greaves said: “What remained a mystery until now was why sometimes only one twin is diagnosed with leukaemia – leaving clinicians in the dark when it comes to offering advice and reassurance to parents.

“In this new study, we show that the healthy twin often has a small number of pre-leukaemia cells in their blood, which have the same genetic markers as the cancer cells in the sick twin.”

The new findings suggest the risk of the healthy twin developing leukaemia could be more accurately assessed – first by determining whether or not the twins are identical and shared a placenta, and then by tracking the levels of pre-leukaemic cells in their blood.

If the levels of these cells increase and it looked like the healthy twin was going to develop leukaemia, treatment could start at an early stage, giving them the best chance of survival.

Sarah McDonald, deputy director of research at Blood Cancer UK, which funded the work, said: “Acute lymphoblastic leukaemia (ALL) is the most common type of cancer in children, affecting children more often than adults.

“Understanding the mechanism as to how the cancer develops in identical twins, and why often only one develops leukaemia is an important question to answer.

“It helps us understand both the risk of the remaining twin developing leukaemia and provides insight into how leukaemia develops in all children.”


Ford AM, Colman S, Greaves M. (2022) “Covert pre-leukaemic clones in healthy co-twins of patients with childhood acute lymphoblastic leukaemia.” Leukaemia, doi: 10.1038/s41375-022-01756-1

Link: https://www.nature.com/articles/s41375-022-01756-1

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