New blood test spots cancer recurrence up to a year earlier than normal scans
Doctors in the UK were able to spot signs of cancer recurrence in the blood up to a year earlier than normal X-ray or CT scans when the cancer was just a tiny cluster of cells invisible to normal scans.
The new test should allow doctors to hit the tumor earlier and increase the chances of a cure.They also have new ideas for drugs after finding how unstable DNA fuels rampant cancer development.
The research project was on lung cancer, but the processes studied are so fundamental that they should apply across all cancer types.
Lung cancer kills more people than any other type of tumor and the point of the study is to track how it can “evolve” into a killer that spreads through the body.
In order to test for cancer coming back,doctors need to know what to look for.
In the trial, funded by Cancer Research UK, samples were taken from the lung tumor when it was removed during surgery.A team at the Francis Crick Institute, in London, then analyzed the tumor’s defective DNA to build up a genetic fingerprint of each patient’s cancer.
Then blood tests were taken every three months after the surgery to see if tiny traces of cancer DNA re-emerged.The results showed cancer recurrence could be detected up to a year before any other method available to medicine.
The tumors are thought to have a volume of just 0.3 cubic mm when the blood test catches them.
So far, the blood test has served as an early warning system for 13 out of 14 patients whose illness recurred, as well as giving others an all-clear.
In theory, it should be easier to kill the cancer while it is still tiny rather than after it has grown and become visible again.
However, this needs more testing.
Prof. Charles Swanton, one of the researchers from the Francis Crick Institute, said clinical trials can now be set up to ask the fundamental question: If you treat people’s disease when there’s no evidence of cancer on a CT scan or a chest X-ray, can we increase the cure rate?
He said they hope that by treating the disease when there are very few cells in the body that they will be able to increase the chance of curing a patient.
The blood test is actually the second breakthrough in the massive project to deepen understanding of lung cancer.
A bigger analysis showed the key factor – genetic instability – that predicted whether the cancer would return.Multiple samples from 100 patients containing 4.5 trillion base pairs of DNA were analyzed.
DNA is packaged up into sets of chromosomes containing thousands of genetic instructions.
The team at the Francis Crick Institute showed tumors with more “chromosomal chaos” – the ability to readily reshuffle large amounts of their DNA to alter thousands of genetic instructions – were those most likely to come back.
Prof. Swanton said the cancer cells have a system in place where a cell can alter its behavior very rapidly by gaining or losing whole chromosomes or parts of chromosomes, describing the process as “evolution on steroids”.
That allows the tumor to develop resistance to drugs, the ability to hide from the immune system or the skills to move to other tissues in the body.
The first implication of the research is for drug development – by understanding the key role of chromosomal instability, scientists can find ways to stop it.
The scientists say they are only scratching the surface of what can be achieved by analyzing the DNA of cancers.
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