It involves taking blood sample of the patient and examining the pattern of molecules called methyl groups that decorate its DNA. The test uses a colour-changing fluid to reveal the presence of malignant cells. The test, which has been performed with 90% accuracy on 200 samples of different types of cancers and healthy cells, is currently at experimental stage and results require further validation through clinical trials before it can be made commercially available.
According to the research published in ‘Nature Communications’, the test relies on a discovery made by the Queensland team that molecules in cancer DNA called methyl groups appear different compared to those in normal DNA.
In healthy cells, the scientists say, microscopic examination shows methyl groups are spread across the genome. However, the genome of a cancer cell is essentially barren except for intense clusters of methyl groups at very specific locations.
When placed in solution, these clusters of methyl groups cause cancer DNA fragments to fold up into three dimensional nanostructures that like to stick to gold. The researchers designed an assay which uses gold nanoparticles that instantly change colour depending on whether or not these 3D nanostructures of cancer DNA are present. Scientists could distinguish normal DNA from cancer DNA by looking for a colour change in the gold particle solution that was visible to the naked eye within a few minutes.
When the researchers tested this on blood or biopsy samples of cancer patients they found this to be accurate in 90% of cases. The unique signature — which the University of Queensland researchers dubbed as the cancer ‘methylscape’ — appeared in every type of breast cancer they examined. It was also used to detect prostate, bowel and lymphoma cancers.
Currently, biopsy of the suspected tumour is the only confirmative test for cancer detection. It is invasive and relies on the patient noticing a lump, or reporting symptoms that the doctor recognises as a potential sign of cancer.
“Biopsy reports come in one to two weeks,” said Dr Julka. Delayed diagnosis is a big problem in cancer cure in India, say doctors. Survival rate for most cancers stagnates at 20% because a majority of the patients come when the disease is already in the advane or III and IV, stages. “If cancer is detected early, 80% patients can be cured of the disease,” said a senior AIIMS doctor.