Background Smoking has been associated with colorectal cancer (CRC) incidence and mortality in previous studies and might also be associated with prognosis after CRC diagnosis. However, current evidence on smoking in association with CRC prognosis is limited. Patients and methods For this individual patient data meta-analysis, sociodemographic and smoking behavior information of 12 414 incident CRC patients (median age at diagnosis: 64.3 years), recruited within 14 prospective cohort studies among previously cancer-free adults, was collected at baseline and harmonized across studies. Vital status and causes of death were collected for a mean follow-up time of 5.1 years following cancer diagnosis. Associations of smoking behavior with overall and CRC-specific survival were evaluated using Cox regression and standard meta-analysis methodology. Results A total of 5229 participants died, 3194 from CRC. Cox regression revealed significant associations between former [hazard ratio (HR) = 1.12; 95 % confidence interval (CI) = 1.04-1.20] and current smoking (HR = 1.29; 95% CI = 1.04-1.60) and poorer overall survival compared with never smoking. Compared with current smoking, smoking cessation was associated with improved overall (HR<10 years = 0.78; 95% CI = 0.69-0.88; HR≥10 years = 0.78; 95% CI = 0.63-0.97) and CRC-specific survival (HR≥10 years = 0.76; 95% CI = 0.67-0.85). Conclusion In this large meta-analysis including primary data of incident CRC patients from 14 prospective cohort studies on the association between smoking and CRC prognosis, former and current smoking were associated with poorer CRC prognosis compared with never smoking. Smoking cessation was associated with improved survival when compared with current smokers. Future studies should further quantify the benefits of nonsmoking, both for cancer prevention and for improving survival among CRC patients, in particular also in terms of treatment response.

中文翻译：

---

诊断前吸烟和戒烟对结直肠癌预后的影响：来自CHANCES联盟中队列中单个患者数据的荟萃分析。

背景在先前的研究中，吸烟与大肠癌（CRC）的发生率和死亡率有关，并且也可能与CRC诊断后的预后有关。但是，目前有关吸烟与CRC预后的证据有限。患者和方法在基线时收集了14例先前无癌症成年人的前瞻性队列研究中招募的12 414例CRC患者（诊断中位年龄：64.3岁）的这一个人患者数据的荟萃分析，社会人口统计学和吸烟行为信息。并在各个研究中保持一致。癌症诊断后，平均随访5.1年，收集生命状态和死亡原因。使用Cox回归和标准荟萃分析方法评估了吸烟行为与总体生存率和CRC特异性生存率之间的关联。结果共有5229名参与者死亡，其中3194名儿童死亡。Cox回归显示前[危险比（HR）= 1.12; 95％的置信区间（CI）= 1.04-1.20]和当前吸烟（HR = 1.29； 95％CI = 1.04-1.60），与从未吸烟相比，总生存期较差。与当前吸烟相比，戒烟与总体改善（HR <10年= 0.78; 95％CI = 0.69-0.88;HR≥10年= 0.78; 95％CI = 0.63-0.97）和CRC特异性存活率（HR ≥10年= 0.76; 95％CI = 0.67-0.85）。结论在这项大型荟萃分析中，包括来自14项关于吸烟与CRC预后之间关系的前瞻性队列研究的CRC患者的主要数据，与从不吸烟相比，既往和当前吸烟与较差的CRC预后相关。与目前的吸烟者相比，戒烟可以提高生存率。未来的研究应进一步量化不吸烟对预防癌症和改善CRC患者生存率的益处，尤其是在治疗反应方面。