Enstrom J E
Br Med J (Clin Res Ed). 1983 Apr 2;286(6371):1101-5. doi: 10.1136/bmj.286.6371.1101.
A study was conducted to assess how lung cancer and other mortality trends among California physicians had been influenced by the high proportion who had given up smoking since 1950. Several sample surveys indicated that the proportion of California physicians who currently smoked cigarettes had declined dramatically from about 53% in 1950 to about 10% in 1980. During the same period the proportion of other American men who smoked cigarettes had declined only modestly, from about 53% to 38%. Using the 1950 American Medical Directory a cohort of 10 130 California male physicians was established and followed up for mortality till the end of 1979, during which time 5090 died. The information from follow up and death certification was exceptionally good. The standardised mortality ratio for lung cancer among California male physicians relative to American white men declined from 62 in 1950-9 to 30 in 1970-9. The corresponding decline in standardised mortality ratio was from 100 to 63 for other smoking related cancer, from 106 to 71 for ischaemic heart disease, and from 62 to 35 for bronchitis, emphysema, and asthma. The standardised mortality ratio remained relatively constant for other causes of death not strongly related to smoking. The overall ratio declined in all age groups at a rate of about 1% a year. The total death rate among all physicians converged towards the rate among non-smoking physicians. By the end of the study period physicians had a cancer rate and total death rate similar to or less than those among typical United States non-smokers. This "natural experiment" shows that lung cancer became relatively less common on substantial elimination of the primary causal factor, cigarette smoking. Other smoking related diseases also became relatively less common, though factors other than cigarette smoking may have contributed to this change.
一项研究旨在评估自1950年以来，加利福尼亚州医生中肺癌及其他死亡率趋势如何受到大量戒烟者的影响。多项抽样调查表明，加利福尼亚州目前吸烟的医生比例已从1950年的约53%急剧下降至1980年的约10%。同一时期，其他美国男性吸烟比例仅略有下降，从约53%降至38%。利用1950年的《美国医学名录》，建立了一个由10130名加利福尼亚州男性医生组成的队列，并对其进行随访直至1979年底的死亡率情况，在此期间有5090人死亡。随访和死亡证明的信息非常完善。加利福尼亚州男性医生相对于美国白人男性的肺癌标准化死亡率从1950 - 1959年的62降至1970 - 1979年的30。其他与吸烟相关癌症的标准化死亡率相应下降，从100降至63；缺血性心脏病从106降至71；支气管炎、肺气肿和哮喘从62降至35。与吸烟关系不紧密的其他死因的标准化死亡率保持相对稳定。所有年龄组的总体死亡率以每年约1%的速度下降。所有医生的总死亡率趋近于非吸烟医生的死亡率。到研究期末，医生的癌症发病率和总死亡率与美国典型非吸烟者相似或更低。这个“自然实验”表明，在基本消除主要致病因素——吸烟后，肺癌相对不那么常见了。其他与吸烟相关的疾病也相对不那么常见了，尽管除吸烟外的其他因素可能也促成了这一变化。
