摘要
BACKGROUND There is a need to have up-to-date information for various diseases on the risk related to the use of different smoked products and the use of other nicotinecontaining products.Here,we contribute to the information pool by presenting up-to-date quantitative evidence for North America,Europe and Japan and for both lung cancer and chronic obstructive pulmonary disease(COPD)on the relative risk(RR)relating to current vs never product use for each of the three smoked tobacco products,cigarettes,cigars and pipes.AIM To estimate lung cancer and COPD current smoking RRs for the three products using recent data for the three regions.METHODS Publications in English from 2010 to 2020 were considered that,based on epidemiological studies in the three regions,estimated the current smoking RR of lung cancer and/or COPD for one or more of the three products.The studies should involve at least 100 cases of the disease considered,not be restricted to specific lung cancer types or populations with specific medical conditions,and should be of cohort or nested case-control study design or randomized controlled trials.Literature searches were conducted on MEDLINE separately for lung cancer and for COPD,examining titles and abstracts initially,and then full texts.Additional papers were sought from reference lists of selected papers,reviews and metaanalyses.For each study identified,the most recent available data on each product were entered on current smoking,as well as on characteristics of the study and the RR estimates.Combined RR estimates were derived using random-effects meta-analysis.For cigarette smoking,where far more data were available,heterogeneity was studied by a wide range of factors.For cigar and pipe smoking,a more limited heterogeneity analysis was carried out.Results were compared with those from previous meta-analyses published since 2000.RESULTS Current cigarette smoking:For lung cancer,44 studies(26 North American,14 European,three Japanese,and one in multiple continents),gave an overall estimate of 12.14[95%confidence interval(CI)10.30-14.30].The estimates were higher(heterogeneity P<0.001)for North American(15.15,CI 12.77-17.96)and European studies(12.30,CI 9.77-15.49)than for Japanese studies(3.61,CI 2.87-4.55),consistent with previous evidence of lower RRs for Asia.RRs were higher(P<0.05)for death(14.85,CI 11.99-18.38)than diagnosis(10.82,CI 8.61-13.60).There was some variation(P<0.05)by study population,with higher RRs for international and regional studies than for national studies and studies of specific populations.RRs were higher in males,as previously reported,the within-study male/female ratio of RRs being 1.52(CI 1.20-1.92).RRs did not vary significantly(P≥0.05)by other factors.For COPD,RR estimates were provided by 18 studies(10 North American,seven European,and one Japanese).The overall estimate of 9.19(CI 6.97-12.13),was based on heterogeneous data(P<0.001),and higher than reported earlier.There was no(P>0.1)variation by sex,region or exclusive use,but limited evidence(0.05<P<0.1)that RR estimates were greater where cases occurring shortly after baseline were ignored;where bronchiectasis was excluded from the COPD definition;and with greater confounder adjustment.Within-study comparisons showed adjusted RRs exceeded unadjusted RRs.Current cigar smoking:Three studies gave an overall lung cancer RR of 2.73(CI 2.36-3.15),with no heterogeneity,lower than the 4.67(CI 3.49-6.25)reported in an earlier review.Only one study gave COPD results,the RR(2.44,CI 0.98-6.05)being imprecise.Current pipe smoking:Four studies gave an overall lung cancer RR of 4.93(CI 1.97-12.32),close to the 5.20(CI 3.50-7.73)given earlier.However,the estimates were heterogeneous,with two above 10,and two below 3.Only one study gave COPD results,the RR(1.12,CI 0.29-4.40),being imprecise.For both diseases,the lower RR estimates for cigars and for pipes than for current smoking of cigarettes aligns with earlier published evidence.CONCLUSION Current cigarette smoking substantially increases lung cancer and COPD risk,more so in North America and Europe than Japan.Limited evidence confirms lower risks for cigars and pipes than cigarettes.
