SAN FRANCISCO (EGMN) – An unusual pattern of sudden, effortless smoking cessation in long-term smokers may herald the onset of lung cancer in a small subgroup of patients, researchers reported at the World Conference on Lung Cancer.

It has been well documented that lung cancer patients often stop smoking shortly before their diagnosis, with the assumption that symptoms such as shortness of breath, coughing, or pain create a strong motivation for behavior change.

Now a pilot study suggests that in certain lung cancer patients – even some with long-term smoking histories and significant levels of nicotine addiction – smoking cessation occurs in the absence of symptoms or even a focused effort to quit.

“This has led us to speculate that in some cases, spontaneous smoking cessation may be a presenting feature of lung cancer, possibly caused by tumor secretion of a factor interfering with nicotine addiction,” said Dr. Barbara Campling, a medical oncologist with the University of Pennsylvania in Philadelphia.

In a study conducted at the Philadelphia VA Medical Center, 115 smokers and former smokers diagnosed with lung cancer were compared to 101 smokers and former smokers with prostate cancer or to 99 with myocardial infarction.

Former smokers with prostate cancer had quit smoking an average of 23 years before their diagnosis; for myocardial infarction, the average interim was 10 years.

But smoking cessation was a more recent event for lung cancer patients, occurring, on average, just 2.7 years before diagnosis.

Further comparisons among former smokers revealed striking differences among the 3 groups.

“In the general population, you would expect that those who succeeded in quitting smoking would be those who smoked less and were less severely addicted, she said at the meeting sponsored by the International Association for the Study of Lung Cancer. “That is exactly what we found in patients with prostate cancer and myocardial infarction.”

In contrast, current and former smokers with lung cancer had similar levels of cumulative tobacco exposure and identical median scores on a scale measuring severity of addiction – scoring 7 on a scale of 0 (“Didn’t even think about it”) to 10 (“The hardest thing I’ve ever done”).

Surprisingly, many of these lung cancer patients reported they had quit smoking with ease and with no symptomatic “alarm bell” that compelled them to stop.

Among the 55 patients who quit smoking before being diagnosed with lung cancer, 49 (89%) were reportedly asymptomatic at the time.

Nearly a third (17 of 55) reported quitting “with no difficulty,” (0 on a scale of 0-7), even though they were moderately to severely addicted to nicotine based on the Fagerström Test for Nicotine Dependence scale.

“The way some of these patients stop smoking is really quite peculiar,” Dr. Campling said. A typical patient was “someone who had smoked a pack of cigarettes a day for 50 years and wakes up one day and forgets to light a cigarette ... [and then] realizes they don’t need it anymore.”

Dr. Campling and her associates hope their findings will be followed up with a long-term, prospective study of smokers to identify any unusual patterns of smoking cessation that may precede a diagnosis of lung cancer. In the meantime, she suggested that clinicians pay attention to any highly unusual pattern of smoking cessation in a long-term, heavy smoker, just as they would a sudden loss of appetite.

Dr. Carolyn Dresler, moderator of the session and an official discussant of the paper, questioned whether memory distortions and attribution errors may have influenced patients’ recall of their smoking histories and difficulty quitting.

Additionally, little is known about the ease of quitting experienced by the majority of smokers who stop smoking cold turkey, said Dr. Dresler, a cardiac and thoracic surgeon who heads the Arkansas Department of Health.

An audience member from the Netherlands rose to say, however, that she too has noticed lung cancer patients who describe quitting heavy smoking habits without a problem, in the absence of symptoms. “They say it doesn’t taste [right] anymore,” she said.

Dr. Campling and her associates reported no financial disclosures with respect to their study.

Copyright (c) 2009 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

旧金山(EGMN)——研究人员在世界肺癌大会(WCLC)上报告称，长期吸烟者异常而轻松地突然戒烟可能预示一小部分人发生肺癌。

 

现已充分证明，肺癌患者往往在疾病诊断前快速戒烟，且跟肺癌可能的症状如呼吸急促、咳嗽或疼痛引发强烈的戒烟动机无关。

 

目前，一项初步研究发现，某些肺癌患者——甚至有些有长期吸烟史和重度尼古丁成瘾——在无症状前戒烟或努力去戒烟。

 

“我们由此推测在某些情况下，自发戒烟可能是肺癌的一个主要特征，可能是由肿瘤所分泌的一种干扰尼古丁成瘾的因子引起。”费城宾州大学临床肿瘤学专家Barbara Campling博士说道。

 

美国费城退伍军人医学中心(VAMC)对罹患肺癌的115名吸烟者和前烟民与101名罹患前列腺癌的吸烟者和前烟民或99名心肌梗死患者做了对比研究。

 

罹患前列腺癌的前烟民在癌症诊断前平均已戒烟23年，心肌梗死患者则平均戒烟10年。

 

但肺癌患者戒烟时间较短，平均为肺癌诊断前2.7年。

 

对前烟民进一步比较发现，上述3组患者间存在显著差异。

 

“在普通人群中，戒烟成功的预计是抽烟较少和烟瘾较轻的那部分人。”她在国际肺癌研究协会(IASLC)主办的此次会议上说道，“我们发现前列腺癌和心肌梗死患者正是如此。”

 

与之相反，罹患肺癌的现烟民和前烟民具有相似的累积烟雾暴露水平和相同的成瘾严重性量表评分中位数——分数为7(0分代表“甚至没去想这事”，10分代表“所做过的最难以忍受的事”)。

 

令人惊讶的是，许多此类肺癌患者报告称他们可轻易地戒烟，没有“警示” 症状迫使他们这么做。

 

据报道，在55例诊断出肺癌前已戒烟的患者中有49例(89%)在戒烟时无相关症状。

 

即便有些是经尼古丁依赖自评量表(FTND)评分为中至重度尼古丁成瘾的患者，亦有近1/3(17例/55例)患者报告戒烟“没有困难” (困难程度0~7级的0级)。

 

“这些病人当中部分人的戒烟方式确实很奇特。” Campling博士说，“一个典型的例子是，某病人原来每天1包烟，吸了有50年，某天醒来却忘记了点香烟……(然后)意识到他再也不需要吸烟了。”

 

Campling博士和她的同事希望有长期的前瞻性研究跟进他们的发现，对可能在肺癌诊断前的各种异常戒烟模式进行鉴别。她同时建议，医生应注意长期重度吸烟者任何罕见的戒烟模式，就好像他们突然丧失食欲。

 

Carolyn Dresler博士是会议的主持人，也是该报告讨论的正式参与者，他质疑患者是否因记忆扭曲和归因错误而影响对吸烟史和戒烟困难程度的回忆。

 

此外，突然戒烟的大多数吸烟者对所经历的戒烟难易性知之甚少，阿肯色州卫生署长、胸心外科医生Dresler博士说。

 

不过现场一位荷兰听众起身说，她也注意到肺癌患者叙述在症状出现之前可轻松地戒掉大量吸烟的习惯。 “他们讲再也抽不出那种味道了。”她说。

 

Campling博士和她的同事报告称该研究无相关的财务关联。

 

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