Low-yield cigarettes and diminution of small airways lung function in long-term smokers

现代香烟被设计成在香烟中的烟草燃烧时产生少量焦油。焦油含有人类致癌物，长期以来，监测和调节焦油的产量一直是澳大利亚综合烟草控制战略的一部分。这种对焦油的关注暗示了低含量香烟是一种更安全的香烟。然而，最近出现了关于吸低含量香烟是否减少了吸烟的危害的争议。令人担忧的是，肺腺癌（一种最常见于周围小气道的肺癌）的发病率有所增加。这可能是因为低尼古丁含量的香烟，尼古丁和焦油的含量都降低了，吸烟者会更强烈地吸烟，以弥补低尼古丁含量的影响。所谓抽得更猛，是指抽得更大、更频繁，把烟深深地吸进肺里，在呼气前屏住呼吸。这种吸烟方法会导致更多的焦油颗粒沉积在腺癌最常见的肺周围。由于吸烟还与肺部小气道的其他结构变化有关，从而导致气流阻塞，因此我们将测试吸低含量香烟是否比吸高含量香烟与小气道阻塞更大有关。为了测试其机制是否为吸烟方法，我们将仔细描述和量化每个受试者的吸烟模式，包括烟雾样Technegas颗粒在外周肺中的沉积。

The modern cigarette has been designed to produce low yields of tar when the tobacco in the cigarette is burnt. The tar contains human carcinogens, and monitoring and regulating yields of tar has long been part of the comprehensive tobacco control strategy in Australia. This focus on tar has given an implicit endorsement of the low-yield cigarette as a safer cigarette. Recently, however, controversy has emerged about whether smoking low-yield cigarettes has reduced the harm done by smoking. The concern is that adenocarcinoma of the lung, a type of lung cancer that is most common in the small peripheral airways, has increased in frequency. This could be because the low-yield cigarette, with reduced yields of nicotine as well as tar, is smoked more intensely by smokers to compensate for the low nicotine. By smoking more intensely, we mean taking larger and more frequent puffs, inhaling the smoke deeply into the lungs, and holding the breath before expiring. This method of smoking would result in more tar particles being deposited in the peripheries of the lung where adenocarcinoma is most common. Because cigarette smoking has been linked also with other structural changes in the small airways of the lung, resulting in obstruction of airflow, we will test whether smoking low-yield cigarettes is associated with greater obstruction of the small airways than is smoking higher-yield cigarettes. To test whether the mechanism is the method of smoking, we will carefully describe and quantify each subject's pattern of smoking including the deposition of smoke-like Technegas particles in the peripheral lung.