Cancer Cells Survive Treatment by ‘Going to Sleep’
One thing that has been puzzling those with cancer and the medical profession for aeons is the fact that one is never cured of cancer, one is always only in remission, with the chances of it returning at any time, even decades later.
Earlier this year, researchers at The Institute of Cancer Research in London published a study in the journal Leukemia, whereby they claim to have found the answer; the cancer cells can escape the effects of chemotherapy by “going to sleep,” only to wake up years, sometimes even decades later.
By analysing a patient whose bone marrow samples had been taken when he was diagnosed at four years old, as well as those taken when he relapsed as a 25-year-old, after 22 years in remission, they discovered a common genetic lineage linking the original leukaemia and relapsing disease decades later.
Researchers identified a specific DNA mutation in which two genes called BCR and ABL1 fuse together, in cancer cells from both blood samples, taken 22 years apart. They said this showed a common link between the original and the relapsing leukaemia; they also found many new genetic changes had occurred in the cancer cells when the patient relapsed.
The scientists found the reawakened cancer cells bore similarities to a group of cancer pre-cursor cells that pre-dated even the original bout of the disease.
The study provides striking evidence of cancer evolution in action, with cancer cells able to lie dormant to avoid treatment, and then to accumulate new mutations capable of driving a new bout of disease.
Scientists have long suspected dormant cells from original cancer were responsible for relapse, but had no evidence to support the theory – until now!
This study has now suggested the cells that trigger a relapse may have survived because they were growing at a much slower rate than other cancer cells, resisting chemotherapy which attacks rapidly dividing cells.
Blood stem cells regularly fluctuate between being dormant or ‘asleep’ and dividing very quickly, so it seems cancer cells are just borrowing this trick to avoid being killed by chemotherapy.
Prof Mel Greaves, director of the Institute’s Centre for Evolution and Cancer, told the Daily Mirror: “We have always known cancer can come back after many, many years. The big question is how? We think we’re a step closer to that answer now. Hopefully this means we can use what we’ve found to reduce the risk of relapse.”
Prof Greaves added: “In future it might be possible to speed up the growth of these pre-cancerous dormant cells so that they can be targeted and killed using chemotherapy, to reduce the risk of relapse even further.”
Dr Matt Kaiser, head of research at Leukaemia and Lymphoma Research, said there were still too many children whose cancer returns.
“If we can build up a picture of what causes rare cases of late relapse and how we can detect and prevent it, we may be able to deliver more true cures for this terrible disease.“