Background In the U.S., lung cancer death rates have declined for decades, primarily due to pronounced decreases in cigarette smoking. However, it is unclear whether there have been similar declines in mortality rates of lung cancer unrelated to smoking. We estimated trends in U.S. lung cancer death rates attributable and not attributable to smoking from 1991-2018. Methods The study included 30-79-year-olds in the National Health Interview Survey who were linked to the National Death Index, 1991-2014. Adjusted hazard ratios (HRs) for smoking status and lung cancer death were estimated, and age-specific population attributable fractions (PAFs) were calculated. Annual PAFs were multiplied by annual U.S. national lung cancer mortality, partitioning rates into smoking-attributable and smoking-unrelated lung cancer deaths. All statistical tests were two-sided. Results During 1991-2018, the proportion of never smokers increased among both men (35.1% to 54.6%) and women (54.0% to 65.4%). Compared to ever smokers, never smokers had 86% lower risk (HR = 0.14; 95%CI 0.12, 0.16) of lung cancer death. The fraction of lung cancer deaths attributable to smoking decreased from 81.4% (95%CI 78.9, 81.4) to 74.7% (95%CI 78.1, 71.4). Smoking-attributable lung cancer death rates declined 2.7%/year (95%CI -2.9, -2.5) and smoking-unrelated lung cancer death rates declined 1.8%/year (95%CI -2.0, -1.5); these declines accelerated in recent years. Conclusions An increasing proportion of lung cancer deaths are unrelated to smoking, due to declines in smoking prevalence. However, smoking-unrelated lung cancer death rates have declined, perhaps due to decreases in secondhand smoke and air pollution exposure and treatment improvements.

中文翻译：

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1991-2018 年美国吸烟所致和与吸烟无关的肺癌死亡率趋势

背景 在美国，肺癌死亡率几十年来一直在下降，这主要是由于吸烟人数的显着减少。然而，尚不清楚与吸烟无关的肺癌死亡率是否也有类似的下降。我们估计了 1991 年至 2018 年美国肺癌死亡率的趋势，归因于和不归因于吸烟。方法 该研究纳入了国家健康访谈调查中与 1991-2014 年国家死亡指数相关的 30-79 岁人群。估计吸烟状况和肺癌死亡的调整后危险比（HR），并计算特定年龄人群归因分数（PAF）。每年的 PAF 乘以每年美国全国肺癌死亡率，将死亡率分为吸烟引起的肺癌死亡和与吸烟无关的肺癌死亡。所有统计检验都是双面的。结果 1991年至2018年间，男性（35.1%至54.6%）和女性（54.0%至65.4%）从不吸烟的比例均有所增加。与曾经吸烟者相比，从不吸烟者的肺癌死亡风险降低了 86%（HR = 0.14；95%CI 0.12，0.16）。因吸烟导致的肺癌死亡比例从 81.4% (95% CI 78.9, 81.4) 下降至 74.7% (95% CI 78.1, 71.4)。吸烟引起的肺癌死亡率每年下降 2.7% (95%CI -2.9, -2.5)，与吸烟无关的肺癌死亡率每年下降 1.8% (95%CI -2.0, -1.5)；近年来，这种下降速度有所加快。结论 由于吸烟率下降，与吸烟无关的肺癌死亡比例不断增加。然而，与吸烟无关的肺癌死亡率有所下降，这可能是由于二手烟和空气污染暴露的减少以及治疗的改进。