Predictive and prognostic value of folate receptor-positive circulating tumor cells in small cell lung cancer patients treated with first-line chemotherapy

// Jiqiao Shen 1, * , Jing Zhao 1, * , Tao Jiang 1, * , Xuefei Li 2 , Chao Zhao 2 , Chunxia Su 1 and Caicun Zhou 1 1 Department of Medical Oncology, Shanghai Pulmonary Hospital, Thoracic Cancer Institute, Tongji University School of Medicine, Shanghai, 200433, P.R. China 2 Department of Lung Cancer and Immunology, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, 200433, P.R. China * These authors contributed equally to this work Correspondence to: Chunxia Su, email: susu_mail@126.com Keywords: small cell lung cancer, circulating tumor cell, count Received: March 15, 2017 Accepted: March 31, 2017 Published: April 11, 2017 ABSTRACT To assess the predictive and prognostic significance of folate receptor (FR)-positive circulating tumor cells (CTCs) in patients with small cell lung cancer (SCLC) received first-line chemotherapy. Eligible patients with chemotherapy-naïve, unresectable SCLC were enrolled and blood samples were collected. CTCs were enumerated using ligand-targeted polymerase chain reaction (LT-PCR) at baseline, after two cycles of chemotherapy regimen and on disease progression. In total, 80 patients were enrolled and 67 (83.8%) had positive CTC count at baseline (CTCs ≥ 8.7 FU/3mL). The baseline CTC counts in patients with partial response (PR) were significantly higher than those with progression disease (PD) ( P = 0.0365). An obvious reduction of CTC enumeration after two cycles of chemotherapy was significantly correlated with PR ( P = 0.0380), instead of SD ( P = 0.4934). Among positive CTC count group, patients with relative low CTC level had significantly longer progression-free survival (PFS) and overall survival (OS) than those with high CTC level (PFS: 9.1 vs 6.9 months, P = 0.0458; OS: 11.1 vs 8.6 months, P = 0.056). In multivariate analysis, distant metastases (HR = 1.466, P = 0.021) and relative low CTC level (HR = 0.656, P = 0.049) were the independent predictive factors for patients with SCLC received first-line chemotherapy. The present results demonstrated that baseline CTC counts could be the valuable predictive and prognostic biomarker for patients with SCLC received first-line chemotherapy. The reduction of CTC enumeration after two cycles of chemotherapy was a potential predictor of chemotherapeutic response in SCLC.