Prognostic Importance of Circulating Tumor Cells in Nonsmall Cell Lung Cancer: A Prospective Study

Purpose: To investigate the prognostic value of circulating tumor cells (CTCs) and to predict the treatment response in a non-small cell lung cancer (NSCLC).
Methodology: A single-center prospective study involving 93 patients with NSCLC was conducted. Blood samples were analyzed for CTC count before and after chemotherapy. Clinical relevance of CTCs with patient`s characteristics and treatment response were determined.
Results: Higher levels of CTCs were associated with severe stage of NSCLC (p = 0.003), tumor histology (p = 0.014) and metastases (p = 0.013). Significant difference in CTC count was observed in favorable (CTCs < 5) and unfavorable (CTCs ≥ 5) groups. Progression-free survival (PFS) was 5.8 months (range: 5.32 to 6.43) and 2.2 months (range: 1.85 to 3.01) in the favorable and unfavorable groups, respectively (HR: 3.88, 95% CI, p < 0.001). Similarly, overall survival (OS) was 7.3 months (95% CI, 6.51 to 7.92) and 3.9 months (95% CI, 1.99 to 5.13), respectively (HR: 4.8, 95% CI, p < 0.001). Multivariate regression analysis revealed CTCs as strong predictors of OS and PFS. Significant reduction (p < 0.001) in CTC count was also observed after one cycle of chemotherapy.
Conclusion: Patients with low CTC count live longer and remain progression-free for a longer period of time than those with high CTC count. High CTCs can be detected in severe forms of lung cancer and can be used as a valid prognostic marker. However, this assertion requires validation in larger prospective clinical cohorts.

Keywords
Circulating tumor cells; Non-small cell lung cancer; Circulating tumor cell; Prognosis