Posted on March 8th, 2009 by
Measuring changes in cancer cells through a microchip from blood samples may provide a way to monitor treatment effectiveness among patients with advanced non–small cell lung cancer (NSCLC). These results were recently published in the New England Journal of Medicine.
Non–small cell lung cancer accounts for approximately 75-80% of all lung cancers. “Non–small cell” refers to the type of cell within the lung from which the cancer originated. Lung cancer is responsible for more cancer-related deaths than breast cancer, prostate cancer, and colon cancer combined. Newer therapies for NSCLC consist of targeted agents that block the epidermal growth factor receptor (EGFR) pathway.
The EGFR is a pathway that is involved in cell replication and growth. It is often overexpressed or mutated within cancer cells. Through targeting and blocking the EGFR, agents such as Iressa® (gefitinib) and Tarceva® (erlotinib) slow cancer growth.
Oncologists have been attempting to monitor changes that occur in cancer cells among patients treated with EGFR inhibitors. Cancer cells used for monitoring these changes are obtained by extracting tissue or cells from the tumor. Unfortunately, this procedure has inherent risks that include collapse of a lung, pain, increased medical costs, and the risk of not collecting enough cancer cells for laboratory analysis.
Researchers from the Massachusetts General Hospital Cancer Center recently conducted a small clinical trial to evaluate the effectiveness of use of a microchip in collecting and assessing cancer cells obtained from circulating blood. Normally, only one cancer cell is present among approximately one billion blood cells, even in advanced cancers. This has historically made collection of cancer cells through the blood inefficient and difficult.
The microchip tested in this trial can easily capture tens of thousands of cancer cells that are circulating in the blood and have broken away from the advanced sites of cancers. These cells can then be analyzed for changes. This small trial included blood samples from 27 patients with advanced NSCLC. Of these patients 23 had mutations within the EGFR and 10 had received prior therapy with either Tarceva or Iressa.
The researchers concluded that “analysis of circulating tumor cells from the blood of patients with lung cancer offers the possibility of monitoring changes in [the] tumor genotypes during the course of treatment.” Further study including this microchip, which is not yet approved for use, is warranted as procedures that might reduce invasive testing of lung cancer patients could be of benefit.
Patients diagnosed with NSCLC may wish to speak with their physician regarding their individual risks and benefits of participating in a clinical trial further evaluating novel non-invasive testing or other novel screening or therapeutic options. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (http://www.cancer.gov) and http://www.eCancerTrials.com.
Reference: Maheswaran S, Sequist L, Nagrath S, et al. Detection of mutations in EGFR in circulating lung cancer cells. New England Journal of Medicine [early online publication]. July 2, 2008. DOI: 10.1056/NEJMoa0800668.
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