Non-Small Cell Lung Cancer (Tracking Viable Circulating Tumor Cells (CTCs) in Peripheral Blood of Non-Small Cell Lung Cancer Patients Undergoing Definitive Radiation Therapy: Pilot Study Results. Dorsey et al. Cancer Jan 1;121(1):139-49 (2015).
Non-small cell lung cancer (NSCLC), which comprises close to 90% of all lung cancers, is the most common cause of cancer mortality in the United States, with more than 224,000 individuals diagnosed every year. Standard follow-up of patients after radiation therapy (RT) often includes imaging modalities such as computed tomography (CT). Unfortunately, CT images can often be confounded post-radiation therapy due to the effects of fibrosis, which can resemble relapsed disease on the image. Therefore, a reliable, CT-independent means to assess disease status would be helpful, especially if the test is biologically relevant, non-invasive, and can be performed in a serial manner with low risk to the patient. The goal would be to have an assay that fits these criteria and could assist in the diagnosis and treatment decisions. Figure 1 below, which was adapted from Dorsey et al., illustrates a correlation between radiographic imaging, tumor status, and CTC analysis.
Figure 1. The three patients shown above (A-C) highlight the potential for serial CTC levels to reflect tumor response to RT. CTC levels in the first two patients (A and B) decreased (56.9 to 0.9 CTC/mL and 3.2 CTC/mL to 0.2 CTC/mL respectively) and these decreases were correlated with radiographic evidence of tumor response. Although the post-RT scans for both patients revealed residual lung thickening, the accompanying low CTC counts bolstered the accurate eventual diagnosis of post-RT scarring over residual disease. In contrast, the third patient (C) had new metastatic disease identified shortly after completing RT and had a corresponding rise in the CTC level post –RT.
Summary: The study demonstrates that Liquid Biotech’s telomerase-based assay can identify CTCs serially in patients undergoing RT for localized NSCLC. Furthermore, it was observed that the CTC counts appeared to reflect the clinical course and response to treatment.