Peripheral lymphocyte subset variation predicts prostate cancer carbon ion radiotherapy outcomes

// Zhang-Ru Yang 1, 2, * , Ning Zhao 2, * , Jin Meng 2, * , Ze-Liang Shi 2 , Bing-Xin Li 2 , Xian-Wei Wu 3 , Ping Li 3 , Qing Zhang 3 , Xun-Bin Wei 1 , Shen Fu 2, 3 1 State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China 2 Department of Radiation Oncology, Shanghai Sixth People’s Hospital of Jiao Tong University, Shanghai, China 3 Radiation Oncology Center, Fudan University Shanghai Cancer Center (FUSCC), Shanghai Proton and Heavy Ion Center (SPHIC), Shanghai, China * These authors have contributed equally to this work Correspondence to: Shen Fu, email: shen_fu@hotmail.com Xun-Bin Wei, email: xwei01@sjtu.edu.cn Keywords: carbon ion radiotherapy, prostate cancer, peripheral lymphocyte Received: November 04, 2015     Accepted: February 29, 2016     Published: March 26, 2016 ABSTRACT The immune system plays a complementary role in the cytotoxic activity of radiotherapy. Here, we examined changes in immune cell subsets after heavy ion therapy for prostate cancer. The lymphocyte counts were compared with acute radiotherapy-related toxicity, defined according to the Common Terminology Criteria for Adverse Events, and short-term local efficacy, defined based on prostate-specific antigen concentrations. Confirmed prostate cancer patients who had not received previous radiotherapy were administered carbon ion radiotherapy (CIR) in daily fractions of 2.74 GyE with a total dose of 63-66 GyE. Lymphocyte subset counts were investigated before, during and after radiotherapy, and at a 1 month follow-up. Most notable among our findings, the CD4/CD8 ratio and CD19+ cell counts were consistently higher in patients with a complete response (CR) or partial response (PR) to CIR than in those classified in the stable disease (SD) group (P<0.05 for both). But CD3+ and CD8+ cell counts were lower in the CR and PR groups than in the SD group. These results indicate that variations in peripheral lymphocyte subpopulations are predictive of outcome after CIR for prostate cancer.