Step by step the treatment of cancer becomes more personalized. The latest advance, in research from John’s Hopkins University (Baltimore, USA), uses a full-genome DNA sequence of a patient’s cancer to determine its ‘signature.’ Thereafter, in screens of blood tests, that signature – usually consisting of the more obvious chunks of rearranged DNA rather than single gene errors – can be detected and used to interpret the status of that person’s cancer.
The initial tests of the procedures were on six patients with two kinds of cancer. For each of the patients, researchers looked for a variety of gross errors in the DNA of the cancer, especially those caused by fusing of chromosomes. Larger errors, usually several, make a reliable ‘fingerprint’ of the type of cancer in that patient’s body. Detecting it later is mostly a matter of getting a positive match from fragments of tumor DNA in the blood.
The combined tests, now called the ‘Personalized analysis of rearranged ends’ or Pare, is rather expensive owing the cost of the initial cancer DNA sequencing (roughly $7,000-$12,000), but this cost is falling very rapidly. The researchers estimate that within a year or two, the Pare testing will cost no more – and probably less – than today’s CT scan (Computer Tomography). CT is also used to detect cancerous elements, but is almost totally ineffective for microscopic particles.
The Pare test is aimed at detecting cancer after surgery (or other primary treatment). It can be used to monitor for the effectiveness of treatment, for example, if many of the cancer’s signatures are discovered, it may mean there is still cancerous material that has not been treated. It can also be used for long term monitoring of cancer remission.
“Eventually we believe this type of approach could be used to detect recurrent cancers before they are found by conventional imaging methods, like CT scans,” said Luis Diaz, an oncologist at Johns Hopkins who took part in the study.
Professor Peter Johnson, chief clinician at Cancer Research UK, said: “This is another exciting step down the road towards personalised cancer medicine. The detection of DNA changes unique to individual cancers has proved to be a powerful tool in guiding the treatment of leukaemia. If this can be done for other types of cancer like bowel, breast and prostate it will help us to bring new treatments to patients better and faster than ever.”
[Source: The Guardian]