Gastroenterological Cancer Studies

胃癌(GC)被认为是由一系列进行性改变引起的，从正常粘膜向慢性萎缩性胃炎(CAG)、肠上皮化生(IM)、异型增生(DYS)转变，最终发展为癌症。中国之前的工作是在山东省临渠县随机选择3,400名胃癌前病变患者进行队列研究，结果显示胃癌风险与基线病变的严重程度之间存在很强的相关性。最近的工作集中在影响这一队列中转化率的因素上。基线水平的幽门螺杆菌感染是4.5年后进展为DYS/GC的危险因素(OR=1.8，95%CI=1.2-2.6)。进展为DYS/GC的风险随着吸烟频率和持续时间的增加而增加。相比之下，在1989-1990年血清抗坏血酸水平最高的人群中，进展为DYS/GC的风险降低了80%(OR=0.2，95%CI=0.1-0.7)。A型血相对其他血型的OR值在DYS为1.4(95%CI=1.1~1.7)，IM为1.3(95%CI=1.1~1.5)。DYS的OR为1.9(95%CI=1.2~3.0)。DYS和IM的合并OR值分别为2.6(95%CI=1.6~4.3)和1.5(95%CI=0.9~2.3)，提示遗传因素在胃癌前病变的发生中起一定作用。对重复内窥镜筛查的影响的评估(1989、1994和1999)发现，在这一高危人群中，GC死亡率没有下降。最近对临渠县3288名成年人进行的一项横断面研究发现，没有证据表明儿童或成年期间接触宠物或其他家养动物与幽门螺杆菌感染的流行有关。但与农村文化程度较高的人群相比，就餐前不经常洗手(OR=1.7，95%CI=1.0-3.0)、与两人以上同床(OR=2.3，95%CI=1.3-4.2)、在池塘或水沟里洗澡(OR=1.5，95%CI=1.0-2.4)、中等(OR=1.6，95%CI=1.3-2.0)和低(OR=2.3，95%CI=1.9-2.9)的人群Hp感染率较高。未婚或离异减少(OR=0.4，95%CI=0.2~1.0)。这些发现表明，在中国农村人群中，人与人之间的传播是最有可能的幽门螺杆菌感染途径，但通过水传播的接触值得进一步调查。用~(13)C-UBT法检测山东省3~12岁儿童和中国高发区(临渠县98名儿童)和低危区(苍山县101名儿童)幽门螺杆菌(Hp)感染情况。临渠市儿童幽门螺杆菌阳性的儿童比例(69.4%)是苍山儿童(28.7%)的近三倍，这可能是这些邻近人群GC率差异很大的原因之一。在13C-UBT阳性的儿童中，CagA+菌株的比例临曲为88.5%，苍山为81.3%。 在对45,486名女性中的477例结直肠癌病例的分析中，几乎没有证据表明水果或蔬菜的摄入与结直肠癌风险之间存在联系。作为乳腺癌检测示范项目后续研究的一部分，这些女性完成了一份包含62个项目的NCI/Block食物频率问卷。 来自亚特兰大、底特律和新泽西的347例男性病例和1354名男性对照的食道癌数据显示，年收入低于10,000美元的受试者与年收入超过25,000美元的受试者相比，食道癌数据显著增加(白人的OR=4.3，CI=2.1-8.7；黑人的OR=8.0，CI=4.3-15.0)。所有四个主要风险因素：低收入、中/重度酒精摄入、吸烟以及不经常食用生果和蔬菜，几乎是白人(98%)和黑人(99%)鳞状细胞食道癌的主要原因，与白人男性相比，黑人食道癌发病率高达99%。

Gastric Cancer Gastric cancer (GC) is thought to arise from a series of progressive changes, with transformation of normal mucosa to chronic atrophic gastritis (CAG), intestinal metaplasia (IM), dysplasia (DYS) and eventually cancer. Previous work conducted in a cohort study of 3,400 subjects selected at random with precancerous gastric lesions in Linqu County, Shandong Province, China revealed a strong relationship between risk of GC and severity of baseline lesions. Recent work has focused on factors that influence rates of transition in this cohort. Helicobacter pylori (H. pylori) infection at baseline was a risk factor for progression to DYS/GC after a 4.5-year follow-up (OR=1.8, 95% CI=1.2-2.6). The risk of progression to DYS/GC increased with both frequency and duration of cigarette smoking. In contrast, risk of progression to DYS/GC decreased by 80% (OR=0.2, 95% CI= 0.1-0.7) among persons with 1989-1990 serum ascorbic acid levels in the highest tertile. The OR for blood type A relative to other types was 1.4 (95% CI=1.1-1.7) for DYS and 1.3 (95%CI=1.1-1.5) for IM. The OR associated with parental history of GC was 1.9 (95%CI=1.2-3.0) for DYS. The combined OR associated with blood type A and parental history of GC was 2.6 (95% CI=1.6-4.3) for DYS and 1.5 (95%CI=0.9-2.3) for IM, suggesting that genetic factors play a role in development of precancerous gastric lesions. Evaluation of the impact of repeated endoscopic screens (1989, 1994, and 1999) found no reduction in GC mortality in this high-risk Linqu population. A recent cross-sectional study among 3,288 adults in Linqu County found no evidence to suggest that exposure to pets or other domestic animals during either childhood or adulthood was related to the prevalence of H. pylori infection. However, H. pylori seroprevalence was elevated for: infrequent hand washing before meals (OR=1.7, 95%CI=1.0-3.0), sharing a bed with more than two people (OR=2.3, 95%CI=1.3-4.2), washing/bathing in a pond or ditch (OR=1.5, 95%CI=1.0-2.4), and medium (OR=1.6, 95%CI=1.3-2.0) and low (OR=2.3, 95%CI=1.9-2.9) compared to high village education level, and reduced for never being married or being divorced (OR=0.4, 95%CI=0.2-1.0). These findings suggest that person-to-person transmission is the most plausible route of H. pylori infection in this rural Chinese population, but waterborne exposures deserve further investigation. The prevalence of H. pylori in general and CagA+ strains in particular as determined by 13C-UBT was compared among children aged 3-12 years in Shandong Province, China in areas at high (98 children in Linqu County) and low risk (101 children in Cangshan County) of GC . The percent of H. pylori-positive children was nearly three times higher among children in Linqu (69.4%) than in Cangshan (28.7%) and may contribute to the large differential in GC rates in these neighboring populations. Among children positive for 13C-UBT, the proportion of CagA+ strains was 88.5% in Linqu and 81.3% in Cangshan. Colon Cancer There was little evidence of an association between intake of fruits or vegetables and risk of colorectal cancer in an analysis of 477 colorectal cancer cases diagnosed among 45,486 women who completed a 62-item NCI/Block food-frequency questionnaire as part of the Breast Cancer Detection Demonstration Project Follow-up Study. Esophageal Cancer Data from a population-based case-control study of squamous cell esophageal cancer among 347 male cases and 1354 male controls from Atlanta, Detroit, and New Jersey found significantly elevated ORs for subjects with annual incomes less than $10,000 versus incomes of $25,000 or more (OR=4.3, CI=2.1-8.7 for whites; OR=8.0, CI=4.3-15.0 for blacks). The combination of all four major risk factors: low income, moderate/heavy alcohol intake, tobacco use, and infrequent consumption of raw fruits and vegetables, accounted for almost all of the squamous cell esophageal cancers in whites (98%) and blacks (99%) and for 99% of the excess incidence among black compared to white men.