被诊断为癌症后继续吸烟增加死亡风险

一项基于人群的前瞻性上海队列研究结果显示，被诊断为癌症后继续吸烟的男性的全因死亡风险显著高于诊断时戒烟的男性(Cancer Epidemiol. Biomarkers Prev. 2013;22:2404-11)。

这项仍在进行中的上海队列研究由加州癌症预防研究所的Li Tao医生及其同事开展，目的是在1986年1月1日~1989年9月30日入组的超过18,000名中老年男性中探讨生活方式特征与癌症发生之间的关联。研究者通过每年面对面访谈确定患者的吸烟状态。



当前分析纳入的患者的平均年龄为68.8岁，本诊断为癌症后的平均随访时间为5.3年，诊断后的中位生存时间为5.4年。在1,632例入组后发生癌症且符合当前分析纳入标准的男性中，931例在25年随访期间死亡，这些死亡患者中有747例在被诊断为癌症时为吸烟者。在吸烟者中，214例(29%)在诊断时戒烟，197例(26%)在诊断后持续吸烟，336例(45%)在诊断后间歇性吸烟。

研究者在校正诊断年龄、教育水平、诊断前累积吸烟包-年数和治疗方式后发现，诊断后持续或间歇性吸烟者的死亡风险比诊断时戒烟者高76%。诊断后持续吸烟者的中位生存时间为2.1年，而戒烟者为4.4年。使用时间依赖性方法对所有癌症患者进行分析发现，癌症诊断后吸烟者的总体死亡风险比未吸烟者高59%。

对癌症特异性患者进行单独分析发现，诊断后吸烟与未吸烟相比的多变量校正死亡风险比(HR)在肺癌患者中为1.92，在胃癌患者中为1.76，在结直肠癌患者中为1.65，在膀胱癌患者中为3.66。

单纯对癌症诊断后的当前吸烟者进行相似分析发现，与癌症诊断后未吸烟相比，癌症诊断后吸烟与所有患者死亡风险增加79%相关。就具体癌症而言，癌症诊断后吸烟与未吸烟相比的死亡HR在肺癌患者中为2.36，在胃癌患者中为1.63，在结直肠癌患者中为2.31，在膀胱癌患者中为2.95，在前列腺癌患者中为2.27，在所有其他癌症患者中为1.34。

研究者表示，该研究结果对癌症生存者、卫生保健提供者和政策提供者具有重要的公共卫生意义，强调了对诊断癌症的患者进行戒烟干预的重要性，而且表明戒烟对生存有潜在益处。虽然预期诊断癌症的患者会有很大兴趣和动力戒烟，但许多患者承受着较大的身体、心理和社会的压力，这些压力成为患者戒烟的绊脚石。此外，在美国，仅约50%的诊断癌症的吸烟者在诊断时、治疗期间或随访期间接受正式的戒烟咨询。因此，在癌症患者的临床治疗中，患者自我进行的或卫生保健提供者辅助进行的戒烟干预仍有较大的改善空间。此外，应将癌症诊断后持续吸烟可减少生存时间的信息传达给患者及其家属，并且这些信息应被整合入指南和循证临床实践中。

该研究的优点在于知道患者的基线吸烟状态且为前瞻性设计。其缺点在于治疗数据有限，而且仅入组癌症诊断后生存时间≥1年的患者。尽管如此，研究结果强烈支持对癌症生存者实施戒烟干预措施，并提示未来研究应从整体和个体层面上研究可能导致对癌症诊断后吸烟状态关注不足的因素。

该研究获美国公共卫生署资助。研究者声明无经济利益冲突。

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By: SHARON WORCESTER, Internal Medicine News Digital Network

Men who continue smoking after a cancer diagnosis have significantly greater risk of death from any cause than did those who quit smoking at the time of diagnosis, according to findings from the prospective population-based Shanghai Cohort Study.

Of 1,632 men from that ongoing study who developed cancer after enrollment and who were eligible for the current analysis, 931 died during 25 years of follow-up, and 747 of those who died were smokers at the time of their cancer diagnosis. Of these smokers, 214 (29%) quit at the time of diagnosis, 197 (26%) smoked persistently after diagnosis, and 336 (45%) smoked intermittently after diagnosis.
 
After the researchers adjusted for age at diagnosis, education, cumulative number of pack-years of prediagnosis smoking, cancer site, and treatment modalities, the risk of death was 76% greater in those who smoked persistently or intermittently after diagnosis, compared with those who quit at diagnosis, reported Dr. Li Tao of the Cancer Prevention Institute of California, Fremont, and her colleagues.

Median survival was 2.1 years after diagnosis for those who continued smoking, compared with 4.4 years for those who quit, the investigators said.

Using a time-dependent approach, and including all patients with cancer, the overall risk of mortality was 59% greater for smokers vs. nonsmokers after cancer diagnosis.

"When analyzed separately for cancer specific patients, the multivariate-adjusted hazard ratios of death for smoking relative to nonsmoking after cancer diagnosis were 1.92 for patients with lung cancer, 1.76 for patients with stomach cancer, 1.65 for patients with colorectal cancer, and 3.66 for patients with bladder cancer," the investigators wrote.

In a similar analysis that included only current smokers at cancer diagnosis, smoking after cancer diagnosis was associated with a 79% increase risk of death relative to nonsmoking after diagnosis for all patients.

"Among cancer-specific patients, the [hazard ratios] of death for smoking vs. nonsmoking after cancer diagnosis were 2.36 in patients with lung cancer, 1.63 in patients with stomach cancer, 2.31 in patients with colorectal cancer, 2.95 in patients with bladder cancer, 2.27 in patients with prostate cancer, and 1.34 in all other patient with cancer," the investigators said (Cancer Epidemiol. Biomarkers Prev. 2013;22:2404-11).

The Shanghai Cohort Study is investigating the association between lifestyle characteristics and cancer development in more than 18,000 middle-age or older men who were enrolled between Jan.1, 1986, and Sept. 30, 1989. Smoking status is ascertained via annual in-person interviews. Patients in the current analysis had a mean age of 68.8 years and were followed for a mean of 5.3 years after cancer diagnosis. They had a median survival time of 5.4 years after diagnosis.

The findings provide new information about smoking and cancer survival, the investigators said, noting that cancer is the leading cause of death among men in China, and the second leading cause of death among men in the United States.

Tobacco use is the most important recognized cause of cancer-related death, they said, adding that strong evidence demonstrates an association between smoking and cancer risk, and between improved health and smoking cessation.

The impact of smoking after a cancer diagnosis, however, has not been well studied, and existing data are conflicting, they noted.

The findings of the present study, which have important public health implications for cancer survivors, health care providers, and policy makers, underscore the importance of smoking cessation interventions – and the potential benefit of cessation on survival – in patients who are diagnosed with cancer, they said.

Although patients diagnosed with cancer are expected to "show great interest and motivation to quit smoking," many face physical, psychological, and social stress that impedes their ability to do so. Furthermore, only about 50% of smokers diagnosed with cancer in the United States receive formal smoking cessation counseling at diagnosis, during treatment, or during follow-up visits, they noted.

"Therefore, there is noticeable room for the improvement of self-managed or health care provider–assisted smoking cessation in the clinical setting of patients with cancer," they wrote, also noting that the message about inferior survival among those who continue smoking after a cancer diagnosis should be conveyed to patients and their families, and should be included in guidelines and evidence-based clinical practices.

This study has considerable strengths – such as knowledge of baseline smoking status and the prospective design. It also has limitations, including limited treatment data and inclusion of only patients who survived 1 or more years after cancer diagnosis.

Nonetheless, the findings provide strong support for smoking cessation intervention programs that target cancer survivors and should inform future research into the contextual and individual-level factors that may result in inadequate attention to smoking among patients with cancer in the post diagnosis setting, the investigators concluded.

This study was supported by grants from the United States Public Health Service. The costs of publication were defrayed in part by the payment of page charges. The authors reported having no disclosures.