Monday, July 14, 2008

Promising new tool for monitoring lung cancer

A non-surgical technique that may help doctors monitor how well non-small cell lung cancer patients are responding to treatment is currently being tested. Using a device known as a CTC-chip to analyze circulating tumour cells from patient's blood samples, it was possible to identify whether patients had genetic mutations that would make them less likely to respond to certain therapies.

The research, published in the New England Journal of Medicine, is still in the early stages. However, if future studies confirm it works, the technique could offer lung cancer patients a non-invasive, safe way to monitor their disease and find out which treatments will work. Currently, in order to get that type of information, patients would have to undergo dangerous, invasive procedures to sample tissues and cells.

The current findings will need to be replicated in larger studies before the chip is used widely, since only 27 patients participated in the pilot study.

The CTC-chip opens up a whole new field of studying tumors in real time. When the device is ready for larger clinical trials, it should provide new ways of measuring treatment response, defining prognostic and predictive measures, and studying the biology of blood-borne metastasis, which is the primary method by which cancer spreads and becomes lethal.

Blood samples from 27 patients, 23 of whom had a cell-surface protein mutation known as the epidermal growth factor receptor (EGFR) mutation were tested. Using the CTC-chip, the researchers were able to identify the mutation from the circulating blood tumour cells 92% of the time.

It was also noticed the chip could detect changes over time. Research has shown that tumours with the EGFR mutation are more likely to respond to a class of drugs known as tyrosine kinase inhibitors, or TKIs; Tarceva (erlotinib) and Iressa (gefitinib) are 2 TKIs used to treat lung cancer. However, the patient's tumours eventually come back. Using the CTC-chip, the researchers found out why; it appears that the tumour cell's genetic makeup evolved over the course of treatment.

Biopsy samples taken at the time of diagnosis can never tell us about changes emerging during therapy or genotypic differences that may occur in different sites of the original tumour, but the CTC-chip offers the promise of noninvasive continuous monitoring.

This information could one day help doctors see when a patient was becoming resistant to treatment so that new therapies could be tried earlier. However, there is still work to do to make this technique more efficient on the larger scale outside of the clinical trial setting.

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