Department of Preventive Medicine, Faculty of Medicine, Saga University, Saga, Japan.
J Epidemiol. 2010;20(2):128-35. doi: 10.2188/jea.je20080093. Epub 2010 Feb 6.
Young age at onset of smoking is a known risk factor for cancer; however, few studies have investigated the risk of cancer associated with onset of smoking during adolescence in Japan.
We analyzed a portion of the data from a population-based cohort of 40 897 subjects aged 40 to 69 years with a history of smoking and no history of cancer at baseline.
During a 14-year follow-up period, 4386 total cancers and 681 lung cancers were newly diagnosed. As compared with smokers who started smoking after the age of 20 years, those who started before the age of 17 years smoked a significantly larger number of cigarettes per day for a significantly longer duration; they also had a significantly higher risk of lung cancer. The hazard ratios in men and women were 1.48 (95% confidence interval, 1.11-1.96) and 8.07 (2.34-27.85), respectively. After further adjustment for smoking amount, the associations remained significant. There was a statistically significant inverse correlation between lung cancer risk and age at onset of smoking in male current smokers whose baseline age was 50 to 59 years; no such association was detected among other age strata.
There was no clear evidence of increased risk of cancer due to adolescent smoking. However, adolescent smoking appeared to indirectly increase lung cancer risk because it was associated with a longer duration and larger amount of smoking.
吸烟起始年龄较小是癌症的已知危险因素；然而，在日本，很少有研究调查青少年时期开始吸烟与癌症风险之间的关系。
我们分析了一项基于人群的队列研究的一部分数据，该研究纳入了 40897 名年龄在 40 至 69 岁、有吸烟史且基线时无癌症史的受试者。
在 14 年的随访期间，共诊断出 4386 例癌症和 681 例肺癌。与 20 岁以后开始吸烟的吸烟者相比，17 岁以前开始吸烟的吸烟者每天吸烟的支数明显更多，持续时间明显更长；他们肺癌的风险也显著更高。男性和女性的风险比分别为 1.48（95%置信区间，1.11-1.96）和 8.07（2.34-27.85）。进一步调整吸烟量后，相关性仍然显著。在基线年龄为 50 至 59 岁的男性当前吸烟者中，肺癌风险与吸烟起始年龄之间存在统计学上显著的负相关；在其他年龄组中未发现这种关联。
没有明确的证据表明青少年吸烟会增加癌症风险。然而，青少年吸烟似乎间接地增加了肺癌风险，因为它与更长的吸烟时间和更大的吸烟量有关。
