New technique for cancer monitoring

21 February 2010
Posted by Chris Smith.

Scientists have discovered a new trick for keeping tabs on cancers.

One of the most malignant aspects of cancer is the ability of the disease to spread to other parts of the body, a process termed metastasis. Normal (left) versus cancerous (right) mammography image.And although surgery or localised treatments like radiotherapy can target the initial disease very effectively, it is usually metastatic spread and disease recurrence from a remote site that ultimately leads to the demise of the affected individual.

But tracking down these remote tumour deposits and detecting their activity can be very difficult, especially when they are small, so it's often impossible to give precise prognostic information to the patient.

Now, however, scientists at Johns Hopkins in the US have developed a new, highly sensitive, genetic test that looks for signature DNA changes that are peculiar to an individual patient's cancer.

The new technique, which is published in the journal Science Translational Medicine and has been dubbed PARE - short for Personalised Analysis of Rearranged Ends - works by looking for DNA rearrangements; that is chunks of entire chromosomes that have swapped places with each other.

This process occurs quite commonly in cancers, but the pattern of rearrangements will be unique to any individual patient's tumour. What study author Victor Velculescu and his colleagues have found is that the levels of these rearranged DNA sequences in the bloodstream can be used to quantify the tumour burden in a patient's body, follow the response of the cancer to treatment and then monitor for evidence of recurrence; in fact the technique is so sensitive that it can potentially pick up evidence of disease activity long before anything is visible on ascan.

This means that, in instances of relapse, doctors could intervene with chemotherapy much sooner, potentially improving the prospects for the patient. The downside of the approach is that it is currently very expensive. It involves sequencing their entire genome, meaning that the price tag is over 5 times higher than a CT scan, the current gold standard for detection of disease recurrence.

But with sequencing costs dropping all the time, in all likelihood this won't remain an obstacle for long. "If current trends in genome sequencing continue, PARE will be more cost effective than CT scans and could prove to be more effective," says Kenneth Kinzler, Professor of Oncology at Johns Hopkins.

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