Cigarette smoking complements the prognostic value of baseline plasma Epstein-Barr virus deoxyribonucleic acid in patients with nasopharyngeal carcinoma undergoing intensity-modulated radiation therapy: a large-scale retrospective cohort study

// Jia-Wei Lv 1, * , Yu-Pei Chen 1, * , Guan-Qun Zhou 1, * , Ling-Long Tang 1 , Yan-Ping Mao 1 , Wen-Fei Li 1 , Rui Guo 1 , Ai-Hua Lin 2 , Jun Ma 1 , Ying Sun 1 1 Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, People’s Republic of China 2 Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, People’s Republic of China * These authors have contributed equally to this work Correspondence to: Ying Sun, e-mail: sunying@sysucc.org.cn Key words: baseline plasma EBV DNA, cigarette smoking, intensity-modulated radiation therapy, nasopharyngeal carcinoma, prognostication Received: December 12, 2015 Accepted: February 11, 2016 Published: February 23, 2016 ABSTRACT We evaluated the combined prognostic value of cigarette smoking and baseline plasma Epstein-Barr virus deoxyribonucleic acid (EBV DNA) in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT). Of consecutive patients, 1501 with complete data were eligible for retrospective analysis. Smoking index (SI; cigarette packs per day times smoking duration [years]), was used to evaluate the cumulative effect of smoking. Primary end-point was overall survival (OS); progression-free survival (PFS), distant metastasis-free survival (DMFS) and locoregional relapse-free survival (LRFS) were secondary end-points. Both cigarette smoking and baseline plasma EBV DNA load were associated with poorer survival ( P