Circulating Tumor Cells as a Biomarker in Lung Cancer

For many decades, scientists were looking for less invasive methods to detect cancer early and to monitor its progression following therapeutic interventions. The practice of biopsying the cancerous organ may not suit all instances especially when they appear in places such as in the lungs. Therefore, it was empirical to find alternatives for the dangerous as well as rather uncomfortable practice of biopsying and according to scientists, circulating tumor cells (CTC) may hold the key in resolving this issue.

What are tumor cells?

As the name suggest, circulating tumor cells are cancer cells, which originate from a location where the tumor resides. However, these cells would be circulating throughout the body instead of being present at a particular location. In leukemias and lymphomas, the phenomenon of circulating tumor cells is obvious as the cancer itself is present in circulating blood cells. However, in solid tumors such as the ones in the breast, lung, prostate…etc, presence of such cells in the circulation and recognizing the same would have wide-ranging consequences towards managing that condition.

What is a biomarker?

Biomarker is a substance, which indicates the state of a biological process and could be introduced externally into the body or else may have been generated within the body itself. It is used in medicine to assess normal biological processes, pathological processes or else to assess the effect of certain therapeutic procedures. In most instances, biomarkers are obtained from the peripheral blood and would facilitate early detection of certain abnormalities before they become clinically apparent.

What is the scientific evidence to suggest the possibility of using CTCs as a biomarker for lung cancer?

In a paper presented at the fourth American Association for Cancer Research (AACS) scientific sessions, researchers believe that circulating tumor cells (CTCs) may be a promising alternative, noninvasive source of tumor materials for biomarker assessment.

The paper was entitled “biomarker analyses using circulating tumor cells” and was presented by Siminder K. Atwal, a senior research associate at Genentech. The paper illustrated the data gathered from analyzing whole blood samples of patients with lung and breast cancers. The researchers were able to detect epidermal growth factor receptor (EGFR) protein expression in CTCs from patients with lung cancer and HER2 expression or amplification in CTCs in patients with metastatic breast cancer. Based on the gathered evidence, the paper concludes that “molecular characterization from captured CTCs is possible and can inform us of the patients’ current biomarker status.” However, they agree that there are limitations in its use and lot needs to be done in order to make it a cost effective and an efficient biomarker.

According to another paper  entitled “serum tumor biomarkers in small cell lung cancer (SCLC)” published in the journal of anticancer research, validation of research platforms and technologies used for detecting circulating tumor cells in relation to small cell lung cancer may improve early detection, prognostication and finally treatment of SCLC with potential novel molecularly-targeted therapeutics. They further emphasizes the need to make use of CTCs as a biomarker when considering that lung cancer accounts for almost 30% of all cancer related mortalities in US with small cell carcinoma accounting for about 15% of all lung cancers with an average five year survival of less than 5%.

However, small cell cancer of the lung is not the only instance where circulating tumor cells would be beneficial as a biomarker, and this was emphasized by a paper published in the journal of American Society of Clinical Oncology titled “Evaluation and Prognostic Significance of Circulating Tumor Cells in Patients With Non–Small-Cell Lung Cancer (NSCLC).” In this paper, researchers conclude that CTCs are detectable in patients with stage IV NSCLC and are a novel prognostic factor for this disease. However, they also agree that further validation is warranted before its routine clinical application.

What does the future hold for CTCs as a biomarker for lung cancer?

The potential for using CTCs as a biomarker for lung cancer remains high and with novel technologies emerging, it may not be far before such techniques can be used in mass scale to counteract the stealthy nature of lung cancers and therefore its lethalness.