Gastroenterological Cancer Studies

胃癌（Gastric Cancer， GC）被认为是由一系列进行性变化引起的，由正常粘膜转变为慢性萎缩性胃炎（CAG）、肠上皮化生（IM）、非典型增生（DYS），最终发生癌变。此前在中国山东省临朐县随机选取3400名胃癌前病变患者进行的队列研究显示，胃癌风险与基线病变严重程度之间存在密切关系。最近的工作集中在影响这一群体转变率的因素上。基线时幽门螺杆菌（h.p ylori）感染是4.5年随访后进展为DYS/GC的危险因素（OR=1.8, 95% CI=1.2-2.6）。进展为DYS/GC的风险随着吸烟的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）。DYS患者A型血相对于其他血型的OR为1.4 (95%CI= 1.1-1.7)， IM患者为1.3 （95%CI=1.1-1.5）。DYS与父母GC病史相关的OR为1.9 （95%CI=1.2-3.0）。与A型血和父母GC史相关的OR在DYS组为2.6 (95%CI= 1.6-4.3)，在IM组为1.5 (95%CI=0.9-2.3)，提示遗传因素在胃癌前病变的发生发展中起作用。对反复内镜筛查（1989年、1994年和1999年）影响的评估发现，在临朐高危人群中，胃癌死亡率没有降低。最近对临朐县3288名成年人进行的一项横断面研究发现，没有证据表明在童年或成年时期接触宠物或其他家养动物与幽门螺杆菌感染的患病率有关。然而,幽门螺杆菌seroprevalence升高:饭前不洗手(OR = 1.7, 95% ci = 1.0 - -3.0),和超过两人同床(OR = 2.3, 95% ci = 1.3 - -4.2),洗涤/沐浴在一个池塘或沟(OR = 1.5, 95% ci = 1.0 - -2.4),和介质(OR = 1.6, 95% ci = 1.3 - -2.0)和低(OR = 2.3, 95% ci = 1.9 - -2.9)相比,乡村教育水平高,和减少从未结婚或离婚(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幽门螺杆菌感染最可信的途径，但水传播暴露值得进一步调查。采用13C-UBT法对山东省3-12岁儿童中幽门螺杆菌（H. pylori）和CagA+菌株（CagA+菌株）的流行情况进行了比较，分析了高发地区（临朐县98例）和低发地区（苍山县101例）儿童幽门螺杆菌的流行情况。临朐县儿童幽门螺杆菌阳性比例（69.4%）比苍山县（28.7%）高出近3倍，这可能是邻近人群中幽门螺杆菌率差异较大的原因。13C-UBT阳性儿童中，临朐区CagA+株比例为88.5%，苍山区为81.3%。

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.