Center for Tobacco Products, US Food and Drug Administration, Silver Spring, MD.
Nicotine Tob Res. 2021 Mar 19;23(4):635-642. doi: 10.1093/ntr/ntaa156.
Studies have shown the health benefits of cigarette smoking cessation. However, the literature remains unclear about the relationship between smoking reduction and health risks. This comprehensive review and meta-analysis updates previous reviews with the newest estimates.
We conducted a systematic review and meta-analysis evaluating the association between smoking reduction and some health risks in observational studies. We defined the following smoking categories: heavy smokers smoked ≥15-20 cigarettes per day (CPD), moderate smokers smoked 10-19 CPD, and light smokers smoked <10 CPD. The relative risks (RRs) and 95% confidence intervals (CIs) were estimated using random-effect models.
We identified 19 studies including four case-control and 15 cohort studies. Compared with continuing heavy smokers, we found decreased lung cancer risk for those who reduced CPD by more than 50% (RR = 0.72, 95% CI: 0.52, 0.91), from heavy to moderate (RR = 0.66, 95% CI: 0.46, 0.85), and from heavy to light (RR = 0.60, 95% CI: 0.49, 0.72). We also found lower risk of cardiovascular disease (CVD) for those who reduced from heavy to light smoking (RR = 0.78, 95% CI: 0.67, 0.89) but not those who reduced by more than 50% and reduced smoking from heavy to moderate. We did not find any significant difference in all-cause mortality, all-cancer risks, and smoking-/tobacco-related cancer risk among those who reduced.
Substantial smoking reduction may decrease lung cancer risk but results on CVD (coronary heart disease and stroke combined) risk were mixed. The relationships between smoking reduction and other endpoints examined were not significant.
This meta-analysis helps clarify our understanding of various smoking reduction levels on some health risks. While smoking reduction may decrease risks of lung cancer, the relationships between smoking reduction and other endpoints, including all-cause mortality and cardiovascular disease, remain unclear. Although smoking reduction may decrease lung cancer risks, the magnitude of lung cancer risk remain high. Among smokers, complete cessation remains the most effective approach for cancer and CVD prevention.
研究表明，戒烟对健康有益。然而，文献对于减少吸烟与健康风险之间的关系仍不清楚。本综述和荟萃分析更新了以前的综述，纳入了最新的估计值。
我们进行了一项系统综述和荟萃分析，评估了观察性研究中减少吸烟与某些健康风险之间的关系。我们定义了以下吸烟类别：重度吸烟者每天吸烟≥15-20 支（CPD），中度吸烟者吸烟 10-19 CPD，轻度吸烟者吸烟<10 CPD。使用随机效应模型估计相对风险（RR）和 95%置信区间（CI）。
我们共纳入了 19 项研究，包括 4 项病例对照研究和 15 项队列研究。与继续重度吸烟相比，我们发现减少 CPD 超过 50%（RR=0.72，95%CI：0.52，0.91）、从重度转为中度（RR=0.66，95%CI：0.46，0.85）和从重度转为轻度（RR=0.60，95%CI：0.49，0.72）的人群肺癌风险降低。我们还发现，从重度转为轻度吸烟的人群心血管疾病（CVD）风险降低（RR=0.78，95%CI：0.67，0.89），但减少 CPD 超过 50%和从重度转为中度的人群 CVD 风险没有降低。我们没有发现减少吸烟的人群在全因死亡率、所有癌症风险和与吸烟/烟草相关的癌症风险方面有显著差异。
大量减少吸烟可能会降低肺癌风险，但 CVD（冠心病和中风合并）风险的结果则喜忧参半。减少吸烟与其他终点之间的关系不显著。
本荟萃分析有助于阐明我们对各种减少吸烟水平对某些健康风险的理解。虽然减少吸烟可能会降低肺癌风险，但减少吸烟与其他终点之间的关系，包括全因死亡率和心血管疾病，仍不清楚。虽然减少吸烟可能会降低肺癌风险，但肺癌风险仍然很高。对于吸烟者来说，完全戒烟仍然是预防癌症和心血管疾病的最有效方法。
