Huang J, Seow A, Shi C Y, Lee H P
Department of Community, Occupational and Family Medicine, Faculty of Medicine, National University of Singapore, Singapore.
Cancer. 1999 Jun 15;85(12):2519-25. doi: 10.1002/(sici)1097-0142(19990615)85:12<2519::aid-cncr5>3.0.co;2-6.
Recent epidemiologic studies have suggested that the anatomic distribution of colorectal carcinoma may have undergone a distal to proximal shift over several decades, which has been attributed variously to environmental and genetic factors as well as preventive intervention.
Trends in subsite distribution and the incidence rate of colorectal carcinoma among Chinese in Singapore between 1968 and 1992 were explored using data from the Singapore Cancer Registry (n = 10,489). Age-standardized incidence rates were computed and compared further using age-period-cohort models by subsite and gender.
The proportion of lesions in the distal colon was found to have increased from 23.2% to 24.4% whereas that for the proximal colon and rectum were fairly consistent over the past 25 years. Our results also showed that age-standardized rates have doubled in proximal lesions (2-3% annually) and more than doubled in distal lesions (3-4% annually) whereas rates in rectal carcinoma have shown a slight increase or stability over time. The patterns of change in all subsite tumors could be attributed to a significant birth cohort effect.
The results of the current study suggest that incidence rates have increased rapidly with no distal to proximal shift observed among ethnic Chinese in Singapore over the past 25 years. The pattern of change differs from findings reported in high incidence countries such as the U. S. and parts of Europe, suggesting that the preventive intervention and early diagnostic capabilities that may have played an important role in these countries have had less effect in Asia. The rapid overall increase in the incidence rate of colon carcinoma supports the role of dietary and other environmental factors as possible risk factors.
近期的流行病学研究表明，在过去几十年中，结直肠癌的解剖分布可能已从远端向近端转移，这被归因于环境和遗传因素以及预防性干预措施。
利用新加坡癌症登记处的数据（n = 10489），探讨了1968年至1992年间新加坡华人结直肠癌亚部位分布趋势及发病率。计算年龄标准化发病率，并按亚部位和性别进一步使用年龄-时期-队列模型进行比较。
发现远端结肠病变的比例从23.2%增加到24.4%，而近端结肠和直肠的比例在过去25年中相当稳定。我们的结果还表明，近端病变的年龄标准化发病率翻了一番（每年2%-3%），远端病变的发病率增加了一倍多（每年3%-4%），而直肠癌的发病率随时间略有增加或保持稳定。所有亚部位肿瘤的变化模式可归因于显著的出生队列效应。
本研究结果表明，在过去25年中，新加坡华人的发病率迅速上升，未观察到从远端向近端的转移。变化模式与美国和欧洲部分高发国家报告的结果不同，这表明在这些国家可能发挥重要作用的预防性干预和早期诊断能力在亚洲的效果较差。结肠癌发病率的总体快速上升支持饮食和其他环境因素作为可能的风险因素的作用。
