Rabeneck Linda, Davila Jessica A, El-Serag Hashem B
Department of Veterans Affairs Health Services Research, the Gastroenterology and Health Services Research Sections, Houston, Texas, USA.
Am J Gastroenterol. 2003 Jun;98(6):1400-9. doi: 10.1111/j.1572-0241.2003.07453.x.
Previous studies have reported a migration in the occurrence of colorectal cancer (CRC) toward a proximal colonic location. To assess the potential impact of this, we evaluated recent temporal trends in the United States.
Using the nine population-based cancer registries that constitute the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute, we identified primary CRCs diagnosed between 1978 and 1998. Temporal changes were evaluated for 3-yr time periods. Age-adjusted incidence rates and the proportions of new diagnoses of CRC were calculated by site and by race.
We identified 243,861 individuals with CRC during 1978-1998, 51.1% of whom were men. In whites and in blacks, the proportions of new diagnoses of right CRC rose significantly, from 34% and 37% to 40% and 44%, respectively. In contrast, the proportions of left CRC (in whites and blacks) and of rectosigmoid CRC (in whites) decreased significantly over time. For whites and blacks, the age-adjusted incidence rates for right CRC remained unchanged (in whites) or showed a small increase (in blacks), whereas the age-adjusted incidence rates for left CRC (in whites and blacks) and for rectosigmoid CRC (in whites) declined. During 1996-1998, right CRC was the most common site in the oldest age groups (70-79, 80 yr, and older) in whites and in blacks.
The proximal migration of CRC over time is not attributed to a true increase in the incidence of right CRC. It is explained by a decrease in the incidence of distal CRC coupled with the aging of the population. Older individuals, in whom the burden of CRC is greatest, and in whom right CRC is the most common site, would be the most adversely affected from CRC screening methods that do not assess the total colon.
既往研究报告称，结直肠癌（CRC）的发病部位有向近端结肠转移的趋势。为评估其潜在影响，我们对美国近期的时间趋势进行了评估。
利用构成美国国立癌症研究所监测、流行病学和最终结果计划的9个基于人群的癌症登记处，我们确定了1978年至1998年间诊断的原发性结直肠癌。对3年时间段的时间变化进行了评估。按部位和种族计算了年龄调整发病率以及结直肠癌新诊断病例的比例。
1978 - 1998年间，我们确定了243,861例结直肠癌患者，其中51.1%为男性。在白人和黑人中，右半结肠癌新诊断病例的比例显著上升，分别从34%和37%升至40%和44%。相比之下，左半结肠癌（白人和黑人）以及直肠乙状结肠癌（白人）的比例随时间显著下降。对于白人和黑人，右半结肠癌的年龄调整发病率保持不变（白人）或略有上升（黑人），而左半结肠癌（白人和黑人）以及直肠乙状结肠癌（白人）的年龄调整发病率则下降。在1996 - 1998年期间，右半结肠癌是白人和黑人年龄最大组（70 - 79岁、80岁及以上）中最常见的部位。
随着时间推移，结直肠癌向近端转移并非由于右半结肠癌发病率的真正增加。这是由于远端结直肠癌发病率下降以及人口老龄化所致。CRC负担最重且右半结肠癌最常见的老年个体，将受到未评估整个结肠的CRC筛查方法的最不利影响。
