A National Study of Survival Trends and Conditional Survival in Nasopharyngeal Carcinoma: Analysis of the National Population-Based Surveillance Epidemiology and End Results Registry

A National Study of Survival Trends and Conditional Survival in Nasopharyngeal Carcinoma: Analysis of the National Population-Based Surveillance Epidemiology and End Results Registry

Cancer Research and Treatment : Official Journal of Korean Cancer Association, April 2017

28421724

Jia-Wei Lv, Xiao-Dan Huang, Yu-Pei Chen, Guan-Qun Zhou, Ling-Long Tang, Yan-Ping Mao, Wen-Fei Li, Ai-Hua Lin, Jun Ma, Ying Sun

Conditional survival (CS) provides important information on survival for a period of time after diagnosis. Currently, information on CS patterns of patients with nasopharyngeal carcinoma (NPC) is lacking. We aimed to analyze survival rate over time and estimate CS for NPC patients using a national population-based registry. Patients diagnosed with NPC between 1973-2007 with at least 5-years follow-up were identified from the Surveillance Epidemiology End. (SEER) registry. Traditional survival rates and crude CS estimates were calculated using Kaplan-Meier analysis. Risk-adjusted survival curves were plotted from the proportional hazards model using the correct group prognosis method. For 7713 patients analyzed, adjusted baseline 5-year overall survival improved significantly from 36.0% in patients diagnosed in 1973-1979, 41.7% in 1980-1989, 46.6% in 1990-1999, to 54.7% in 2000-2007 (P<0.01). CS analysis demonstrated that for every additional year survived, adjusted probability of surviving the next 5 years increased from 66.7% (localized), 54.0% (regional) and 35.3% (distant) at the time of diagnosis, to 83.7% (localized), 75.0% (regional) and 62.2% (distant) for patients who had survived 5 years. Adjusted 5-year CS differed among age, sex, tumor histology, ethnicity, and stage subgroups initially, but converged with time. Treatment outcomes of NPC patients have greatly improved over the decades. Increases in CS become more prominent in patients with distant disease than in those with localized or regional disease as patients survive longer. CS provides more dynamic prognostic information for patients who have survived a period of time after diagnosis.