Several studies have reported inconsistent results about second primary lung cancer (SPLC) after irradiation for initial primary lung cancer (IPLC). The present study aims to assess the effect of ionising radiation on the risk of SPLC. The study population came from SEER database, and included a population-based cohort of 21,397 individuals diagnosed with IPLC between 2004 and 2009 who survived more than 7 years after the initial diagnosis. The first aim was to estimate the risk of SPLC in different periods and the cumulative risk of SPLC. Subsequently, a generalized additive model with Poisson regression analysis and a proportional sub-distribution hazard model was used to determine whether radiation affected the risk of SPLC. Until Dec 2016, there were 488 individuals who developed SPLC, 5368 individuals who died, and there were 15,541 alive individuals, respectively. The risk of SPLC was found to gradually decline with the extent of follow-up time. Age and histology were the two main risk factors of developing SPLC in Poisson regression and competing risk analyses. In Poisson regression analysis, radiation had no significant effect on the risk of developing SPLC (adjusted OR = 0.80, 95% CI 0.54, 1.19, P = 0.28). When considered competing risk of all-cause death, the risk of SPLC in the radiation group was similar to that in the non-radiation group (adjusted sHR = 0.80, 95% CI 0.56, 1.13, P = 0.21). The risk of SPLC was different during different follow-up time. Irradiation for IPLC seemingly did not affect the risk of developing SPLC.

几项研究报告了初始原发性肺癌 (IPLC) 照射后继发性原发性肺癌 (SPLC) 的不一致结果。本研究旨在评估电离辐射对 SPLC 风险的影响。研究人群来自 SEER 数据库，包括 21,397 名在 2004 年至 2009 年间被诊断患有 IPLC 且在初始诊断后存活超过 7 年的人群队列。第一个目的是估计不同时期SPLC的风险和SPLC的累积风险。随后，使用具有泊松回归分析的广义加性模型和比例子分布风险模型来确定辐射是否影响 SPLC 的风险。到 2016 年 12 月，有 488 人患上了 SPLC，5368 人死亡，其中 15 人，分别有541个活着的个体。发现 SPLC 的风险随着随访时间的延长而逐渐下降。在泊松回归和竞争风险分析中，年龄和组织学是发生 SPLC 的两个主要风险因素。在泊松回归分析中，辐射对发生 SPLC 的风险没有显着影响（调整后的 OR = 0.80, 95% CI 0.54, 1.19,P  = 0.28）。当考虑全因死亡的竞争风险时，放疗组的 SPLC 风险与非放疗组相似（调整后的 sHR = 0.80, 95% CI 0.56, 1.13, P  = 0.21）。不同随访时间发生SPLC的风险不同。对 IPLC 的辐照似乎不会影响发生 SPLC 的风险。