Stem Cell Time Bombs Cause Leukaemia Relapse
10 June 2011 - Leukaemia ‘stem cells’ can lie dormant in the body for a decade or more after a child achieves remission before being reactivated and causing a relapse, a new study shows.
Professor Mel Greaves and colleagues at The Institute of Cancer Research, found that some types of treatment eradicate the leukaemic cells, but do not kill all the leukaemic stem cells.
If the patient is exposed to another trigger at a later stage, the cancer can start developing again. The team scanned DNA from cancer samples taken from 21 patients at first diagnosis with acute lymphoblastic leukaemia (ALL) and then at relapse.
By analysing driver mutations present at both stages, they confirmed the cancer cells causing relapse were derived from cells present at first diagnosis, in most cases at low levels.
For one patient, they performed backtracking analysis using a technique called fluorescence in situ hybridization (FISH) and identified a cancer cell present at low levels at diagnosis (0.4%) whose genotype actually matched the dominant cancer cells (79.8%) observed at relapse ten years later.
The study findings raise the possibility that patients at risk of relapse could be identified by using sensitive molecular screening methods to look for a reservoir of leukaemic stem cells.
