胆囊切除与结直肠息肉相关性的研究

背景：胆囊切除已被认为是结直肠癌的危险因素之一,但胆囊切除与结直肠息肉的关系一直未受到重视。目的：探讨胆囊切除与结直肠息肉的相关性。方法：连续收集经结肠镜排除恶性肿瘤、炎症性肠病、家族性腺瘤性息肉病等疾病的患者425例,根据既往有无胆囊切除史分为胆囊切除组（n=63）和对照组（n=362）,对两组患者结直肠息肉的发生率、内镜下息肉表现和组织学类型进行分析。结果：胆囊切除组结直肠息肉发生率高于对照组（46.0%对37.8%）,但差异无统计学意义（P=0.219）。两组患者息肉的部位和形态均无明显差异（P=0.753,P=0.127）;但胆囊切除患者腺瘤性息肉的发生危险显著高于对照组（OR=1.79,P=0.006）。亚组分析示胆囊切除史≥10年的结直肠息肉发生率与胆囊切除史〈10年无明显差异（P=0.11）。结论：胆囊切除并未增加结直肠息肉发生的危险性,但腺瘤性息肉的发生率显著增高,因此对胆囊切除患者应重视早期结直肠癌和腺瘤性息肉的筛查。     

结直肠癌患者血清Ang-2含量检测及意义

目的探讨结直肠癌患者血清血管生成素-2（Ang-2）含量变化的临床意义。方法采用ELISA法分别检测185例结直肠癌患者、46例结直肠腺瘤息肉患者、33例炎症性肠病患者、65例肠道良性病变患者及30例正常对照者血清Ang-2、癌胚抗原（CEA）含量,并检测结直肠癌患者术后各随访组及肿瘤复发组血清Ang-2、CEA含量,分析血清Ang-2含量与结直肠癌病理特征的关系。结果结直肠癌组及肿瘤复发组Ang-2含量显著高于正常组和肠道良性病变组,结直肠腺瘤息肉组及炎症性肠病组Ang-2含量亦明显高于正常组（P均〈0.05）,而CEA含量无明显升高（P〉0.05）。术后各随访组Ang-2与CEA含量较术前均显著降低（P均〈0.01）。结直肠癌组血清Ang-2含量与肿瘤大小、肿瘤分化程度、病理分期均呈正相关（P〈0.05或0.01）。结论血清Ang-2含量可作为一种新的结直肠癌肿瘤标志物,有助于结直肠癌的临床诊断与评价、术后复发及高危对象的监测。     

血浆同型半胱氨酸和血清叶酸水平与结直肠腺瘤性息肉相关性研究

目的了解结直肠腺瘤性息肉患者的血浆同型半胱氨酸和血清叶酸水平,并探讨之间的关系。方法选取42例结直肠腺瘤性息肉患者和46例健康对照者,测定其血浆同型半胱氨酸水平及血清叶酸水平。结果结直肠腺瘤性息肉患者的血浆同型半胱氨酸水平显著高于健康对照者（15.04μmol/L±4.80μmol/Lvs8.23μmol/L±3.70μmol/L,P〈0.001）,血清叶酸水平显著低于健康对照者（4.46 ng/mL±3.63 ng/mLvs13.65 ng/mL±4.86 ng/mL,P〈0.001）。结论结直肠腺瘤性息肉与血浆同型半胱氨酸水平升高和血清叶酸水平降低之间存在一定联系,可能是结直肠腺瘤性息肉的危险因素,有必要对此作进一步的探讨。     

用抗人结肠癌单克隆抗体检测血清和粪便中大肠癌相关抗原的研究

目的 研究抗人结肠癌MAb检测血清及粪液中癌相关抗原的价值。 方法 采用抗人结肠癌单抗SC_(3A)和SC_6检测47例结直肠癌、33例结直肠腺瘤、15例增生性息肉、14例炎性息肉及60例正常人群的血清和粪便中癌相关抗原。经ELISA双抗体夹心法检测。 结果 血清和粪便阳性率在结直肠癌组分别为66.0％和72.3％;腺瘤组为63.6％和60.6％;增生性息肉组为35.7％和57.1％;炎性息肉组为40.0％和33.3％;而正常对照组仅为11.7％和13.3％。45例大肠癌Dukes分期进行检测,早期癌粪便检测的阳性率为72.2％,而血清为50.0％。 结论 ELISA法检测不仅对大肠癌及癌前病变具有较好的敏感性,而且对早期癌及癌前期病变检测较血清学检测意义更大。此外,随腺瘤不典型增生程度加重而检测阳性率增高。粪便中检测大肠癌相关抗原,方法简便,取材容易,具较好敏感性,对大规模人群普查大肠癌具有一定的应用价值。     

转化生长因子-β1、Smad3、Smad4和Smad7在结直肠癌发生中的作用

结直肠腺瘤-腺癌序列是目前公认的结直肠癌发生学说，但关于结直肠腺瘤，特别是高危型结直肠腺瘤中转化生长因子（TGF）-β1通路蛋白表达的临床研究较少。目的：探讨TGF—β1、Smad3、Smad4和Smad7在结直肠癌发生中的作用。方法：选取2000年8月-2006年12月六安市人民医院结直肠息肉标本110例（包括腺瘤性和非腺瘤性息肉）、结直肠癌40例和正常结直肠组织20例，以免疫组化染色检测TGF—β1、Smad3、Smad4和Smad7在各组中的表达．并分析高危型腺瘤中TGF-IM、Smad3、Smad4和Smad7表达与临床病理特征的关系。结果：TGF-IM、Smad3、Smad4、Smad7在息肉组、结直肠癌组和对照组中的表达有显著差异（P〈0．05），其表达与高危型腺瘤患者的临床病理特征均不相关。高危型腺瘤和DukesA期结直肠癌中TGF-IM、Smad3、Smad7的表达有显著差异（P〈0．05），而Smad4表达无显著差异。结论：TGF—β1通路可能参与了结直肠癌的发生过程，TGF—β1、Smad3和Smad7可能在结直肠腺瘤的癌变早期起作用。     

散发性大肠腺瘤性息肉患者粪便中APC基因突变的意义及与中医体质的关系

[目的]观察粪便中散发性大肠腺瘤性息肉APC基因突变的意义,探讨易出现APC基因突变的中医体质类型。[方法]采用QIAamp DNA Stool Mini Kit 51504提取42例大肠腺瘤性息肉、8例非腺瘤性息肉、12例大肠癌患者及23例正常人群粪便的DNA,运用聚合酶链反应—单链构象多态分析法(PCR-SSCP)检测APC基因的突变情况;通过问卷形式调查散发性大肠息肉患者的中医体质类型。[结果]42例大肠腺瘤性息肉患者的粪便APC基因的突变率为21.43%(9/42);8例非腺瘤性息肉及23例正常组APC基因的突变率均为0;12例大肠癌患者粪便中APC基因突变率为33.33%(4/12);总突变率为15.30%。腺瘤性息肉组与正常组比较差异有统计学意义(P0.05);腺瘤性息肉与大肠癌组比较差异无统计学意义(P0.05)。粪便APC基因突变与中医体质无关(P0.05)。[结论]检测粪便中APC基因的突变率有助于大肠腺瘤性息肉筛查,大肠腺瘤性息肉粪便中APC基因的突变与中医体质无明显关系。     

粪便SDC2基因甲基化检测在结直肠癌早期诊断中的应用价值

目的 探讨粪便SDC2基因甲基化检测在结直肠癌早期诊断中的应用价值。方法 采用定量甲基化特异性PCR技术检测接受结直肠癌（CRC）筛查的患者粪便样本中SDC2的甲基化（mSDC2）,SDC2基因甲基化检测阳性患者进一步行结肠镜检查,患者均通过结肠镜检查或术后病理检查腺癌（CRC）明确诊断,病理区分为结直肠癌、进展型腺瘤、非腺瘤性息肉、炎症。采用Pearson相关法分析SDC2基因甲基化检测结直肠肿瘤阳性预测值（PPV）与年龄的相关性。结果 纳入268例mSDC2阳性患者,其中确诊结直肠癌23例、进展型腺瘤42例、非腺瘤息肉20例、炎症18例,余下患者结肠镜检查未发现明显异常。<60岁结直肠癌患者SDC2基因甲基化检测PPV为7.04%(10/142),≥60岁者为30.23%(13/43);mSDC2在结直肠癌患者中的PPV随着年龄增长而增加,差异有统计学意义（P<0.05）。随年龄增长,mSDC2循环阈值与年龄呈负相关（r=-0.68,P<0.05）。结直肠癌患者mSDC2的Ct值比进展型腺瘤、非腺瘤息肉、炎症病变均低,差异有统计学意义（P均<0.05）。按m...     

代谢综合征组分与结直肠腺瘤性息肉复发关系的研究

背景：研究显示一些代谢综合征（MS）组分为结直肠腺瘤性息肉的危险因素,然而关注MS组分在结直肠腺瘤性息肉复发中意义的研究尚少。目的：研究MS组分与结直肠腺瘤性息肉复发的关系。方法：纳入2003年1月～2009年1月于北京大学人民医院行内镜下结直肠息肉切除术、病理诊断为腺瘤性息肉并有2年以上复查资料的成年患者,采集其包括4项MS组分（肥胖、高血压、高血糖、血脂异常）在内的12项可疑危险因素,筛选复发相关因素,以之为自变量,以研究起点之后第1～3年期间的结肠镜复查结果为因变量,行多元logistic回归分析,计算OR值并换算为RR值。结果：共138例患者纳入研究,76例（55.1%）在研究起点之后第1～3年期间复发,4例复查时发现结直肠癌年龄、高血压病史、糖尿病病史、饮酒史和多发性腺瘤以及伴发MS组分的数量与复发相关（P〈0.05）。logistic回归分析显示MS组分（OR=2.308,P〈0.01：RR=1.342）和年龄（OR=1.040,P〈0.05;RR=1.018）为复发的独立危险因素。结论：伴发MS组分的结直肠腺瘤性息肉更易复发,提示可将MS组分纳入结直肠腺瘤性息肉治疗后复查的参考指标。     

PUMA、COX-2、Caspase-3在结直肠癌中的表达及临床意义

目的进一步探讨结直肠癌的发生机制。方法选择手术切除的结直肠癌标本60份（结直肠癌组）、腺瘤组织20份（腺瘤组）,另取癌组织切缘正常黏膜44份（正常组）,采用免疫组化法检测其p53上调凋亡调控因子（PUMA）、环氧合酶-2（COX-2）、半胱氨酸天冬氨酸蛋白酶-3（Caspase-3）表达情况,采用计数资料列联表的相关分析法分析三指标间及与结直肠癌临床病理特征的关系。结果结直肠癌组PUMA、COX-2、Caspase-3阳性表达率分别为31.7%7、8.3%6、6.7%,腺瘤组分别为30.0%、75.0%、70%,正常组分别为63.6%、84.1%、95.5%,结直肠癌和腺瘤组PUMA、Caspase-3阳性表达率明显低于正常组,P均〈0.01;COX-2阳性表达率亦低于正常组,P均〉0.05;结直肠癌组和腺瘤组三指标间阳性率比较均无统计学差异。PUMA的表达与结直肠癌肿瘤直径相关,与其他临床病理特征无关;Caspase-3和COX-2的表达均与结直肠癌中临床病理参数无关。PUMA与Caspase-3表达呈正相关。结论 PUMA和Caspase-3的表达下调可能在结直肠癌发生的早期阶段起作用。     

粪便肿瘤型M2丙酮酸激酶在胃肠道肿瘤检测中的意义

肿瘤型M2丙酮酸激酶（M2-PK）是近年发现的一种新型肿瘤标志物。目的：评价粪便肿瘤型M2-PK在胃肠道肿瘤和癌前状态的检测以及肿瘤分期中的意义。方法：以酶联免疫吸附测定（ELISA）检测34例胃癌、31例结直肠癌、19例胃肠道息肉、26例慢性萎缩性胃炎和19例对照者的粪便肿瘤型M2-PK值，胃癌和结直肠癌患者同时行传统外周血肿瘤标志物癌胚抗原（CEA）、糖链抗原（CA）19-9和CA24-2水平检测。结果：胃癌组和结直肠癌组的粪便肿瘤型M2-PK检测值和阳性率均较对照组显著增高（P〈0．01），胃肠道息肉组的检测值亦较对照组显著增高（P〈0．05）。随着肿瘤临床病理分期的进展和转移的发生，粪便肿瘤型M2-PK检测值逐渐增高（胃癌组：P〈0．05；结直肠癌组：P〈0．01）。胃癌组和结直肠癌组粪便肿瘤型M2-PK检测的阳性率均显著高于血清CEA、CA19．9和CA24．2（P〈0．01）。结论：粪便肿瘤型M2-PK对胃肠道肿瘤和癌前状态之一的胃肠道息肉的诊断有一定临床意义。     

Methylenetetrahydrofolate reductase C677T genotype affects promoter methylation of tumor-specific genes in sporadic colorectal cancer through an interaction with folate/vitamin B12 status

AIM： To evaluate joint effects of Methylentetra- hydrofolate reductase （MTHFR） C677Tgenotypes, and serum folate/vitamin B12 concentrations on promoter methylation of tumor-associated genes among Iranian colorectal cancer patients.
METHODS： We examined the associations between MTHFR C677T genotype, and promoter methylation of P16, hMLH1, and hMSH2 tumor-related genes among 151 sporadic colorectal cancer patients. The promoter methylation of tumor-related genes was determined by methylation-specific PCR, Eighty six patients from whom fresh tumor samples were obtained and 81 controls were also examined for serum folate and vitamin B12 concentrations by a commercial radioimmunoassay kit.
RESULTS： We found 29.1% of cases had tumors with at least one methylated gene promoter. In case-case comparison, we did not find a significant association between methylation in tumors and any single genotype. However, in comparison to controls with the CC genotype, an increased risk of tumor methylation was associated with the CT genotype （OR = 2.5; 95% CI, 1.1-5.6）. In case-case comparisons, folate/vitamin B12 levels were positively associated with tumor methylation. Adjusted odds ratios for tumor methylation in cases with high （above median） versus low （below median） serum folate/vitamin B12 levels were 4.9 （95% CI, 1.4-17.7）, and 3.9 （95% CI, 1.1-13.9）, respectively. The frequency of methylated tumors was significantly higher in high methyl donor than low methyl donor group, especially in those with MTHFR CT （P = 0.01）, and CT/TT （P = 0.002） genotypes, but not in those with the CC genotype （P = 1.0）.
CONCLUSION： We conclude that high concentrations of serum folate/vitamin B12 levels are associated with the risk of promoter methylation in tumor-specific genes, and this relationship is modified by MTHFR C677T genotypes.     

Fecal Lysozyme: An Unreliable Marker for Colorectal Cancer

High levels of lysozyme have been reported to be present in the feces of patients with colorectal cancer. It has been suggested that fecal lysozyme could prove useful in the early detection of colorectal cancer, but that further work is needed. The present investigation reports on the measurement of fecal lysozyme in 23 colorectal cancer patients and 39 healthy controls. The mean fecal lysozyme level for the cases was 13.3 +/- 2.8 micrograms/g stool compared with 12.5 +/- 2.6 micrograms/g stool for the controls. The median level for the cases was 8.7 micrograms/g stool compared with 6.6 micrograms/g stool for the controls. Forty-three percent of the cases and 31% of the controls had fecal lysozyme levels above 10 micrograms/g stool. None of these differences were statistically significant. The results of this study indicate that fecal lysozyme would be of no use in the early detection of colorectal cancer.     

Asymptomatic colorectal neoplasia and fecal characteristics: a case-control study of subjects participating in the nottingham fecal occult blood screening trial

PURPOSE: The results of previous studies of colorectal neoplasia and fecal composition have been inconsistent, in part because the cases have been symptomatic and the studies small. We sought to test hypotheses relating to fecal bile acids, calcium, and pH in a large sample of asymptomatic subjects who had participated in fecal occult blood screening. METHODS: Fecal samples were obtained from 45 cases of cancer, 129 subjects with adenoma, 167 fecal occult blood-negative controls and 155 fecal occult blood-positive subjects in whom no cancer or adenoma was found. Concentrations of fecal bile acids, steroids, calcium, and pH were assessed blind to case-control status and compared between cases and 1) fecal occult blood-negative controls and 2) fecal occult blood-positive subjects. RESULTS: No association between colorectal cancer and fecal bile acids or pH was observed. Although there was no overall association between colorectal adenomas and fecal bile acids or pH, villous adenomas were associated with increasing concentrations of major bile acids and decreasing concentration of minor bile acids, and there was a suggestion of an inverse association with an acid pH. High levels of fecal calcium were associated with a reduced risk of both colorectal cancer and adenoma, but this was not statistically significant. CONCLUSION: The study does not support an association between colorectal cancer and fecal bile acids or pH. However, there is evidence that increases in major bile acids are associated with villous adenomas.     

Is serum homocysteine level elevated in colorectal tumor?]

BACKGROUND/AIMS: Although it has been known that folate will participate in colorectal carcinogenesis, the relationship between blood folate level and colorectal cancer is less consistent. The blood folate level does not reflect the systemic folate status. By contrast, serum homocysteine has become a sensitive marker for the folate deficiency. We attempted to explain the correlation between folate and colorectal cancer according to the serum homocysteine level. METHODS: We reviewed the clinical records, including alcohol history of 184 patients taking the colonoscopy and measurement of the serum homocysteine level at Health Promotion Center from 2001 to 2002. One hundred fifty-one of 184 were included, excluding 33 patients with previous history of colonic polyp, cerebrovascular, cardiovascular attack and thromboembolism. They were divided into the normal control (n=111) and the adenomatous polyp group (n=40). We had selected the colorectal cancer group (n=50) from the collection list of the tissue and blood bank less than 3 months storage interval. RESULTS: There was no significant difference in the mean serum homocysteine level among three groups. However, in the subjects with high alcohol consumption, there was a significant difference in the mean serum homocysteine between the normal control (n=7) and the adenomatous polyp group (n=9) (10.2 vs 15.1 mumol/L, p<0.05). CONCLUSIONS: There was no correlation of serum homocysteine and colorectal tumor. However, in the subjects with high alcohol consumption, high serum homocysteine might be related to the development of adenomatous polyp.     

联合检测粪便癌胚抗原和钙卫蛋白诊断大肠癌的临床价值

目的联合检测粪便中癌胚抗原（CEA）及钙卫蛋白,探讨其诊断大肠癌的临床应用价值。方法收集北京军区总医院消化内镜中心接受肠镜检查病人的新鲜粪便标本共177例,其中大肠癌48例,结直肠息肉51例,功能性肠病78例。采用ELISA法半定量检测粪便中钙卫蛋白及癌胚抗原浓度,比较其在不同组中的差异;应用ROC曲线确定最佳临界值,并对两个检测指标进行综合评价。结果大肠癌组粪便钙卫蛋白及CEA含量的中位数分别为470（0．9—1380．61）μg,／g,19．42（0．46～109．78）μg／g,高于其余组,差异有统计学意义（P〈0．05）;肿瘤发生部位不同的患者粪便钙卫蛋白及CEA的水平无明显差异（P〉0．05）;ROC曲线分析提示：以12．09μg／g为临界点,CEA诊断大肠癌的灵敏度为73％,特异度为56％;以104．2μg／g为临界点,钙卫蛋白诊断大肠恶性肿瘤的灵敏度为90．1％,特异度为54．2％;钙卫蛋白联合CEA诊断大肠癌的灵敏度为97．3％,特异度为30．35％。结论粪便钙卫蛋白及CEA检测大肠癌有较高的敏感性,且不受肿瘤部位的影响,可以作为门诊筛查大肠癌的标志物。     

Fecal short chain fatty acids in South African Urban Africans and whites

Diminished levels for fecal short chain fatty acids (SCFAs) have been linked to occurrence of ulcerative colitis, colorectal polyps, and colon cancer, diseases that are rare or uncommon in African populations. PURPOSE: The aim of this study was to determine fecal SCFA concentrations and fecal pH values in groups of black South Africans (African) and white South Africans (white) subjects. METHODS: Twenty healthy Africans (all women; mean age, 35 years) and 17 healthy whites (7 women; 10 men; mean age, 32 years) were tested. RESULTS: Mean total concentrations of SCFAs in the two groups were 142.1 (±53.9) and 69.2 (±26.0) mmol/kg wet feces, respectively (P=0.0001). Mean values for Africans were significantly higher in all subfractions except butyrate. There was a significant inverse correlation between fecal pH value and total fecal SCFA concentration (r=0.704;P=0.001). CONCLUSION: High concentrations of fecal SCFAs in the African group could protect against chronic bowel diseases.Abstract presented at the annual meeting of the South African Gastroenterology Society, October 1 to 5, 1993.Supported by the National Cancer Association of South Africa, Kellogg's South Africa, the Anglo-American and De Beers Chairman's Fund, Medical Faculty Research Endowment Fund, University of Witwatersrand, Johannesburg, South Africa.     

Lower serum folate is associated with development and invasiveness of gastric cancer

AIM: To evaluate the associations of serum folate level with development, invasiveness and patient survival of gastric cancer.METHODS: In this nested case-control study, patients with newly diagnosed gastric cancer undergoing gastrectomy were enrolled, and patients receiving chemotherapy prior to surgery, with other concurrent malignancy, or of the aboriginal and alien populations were excluded. In total, 155 gastric cancer patients and 149 healthy controls were enrolled for determination of serum folate levels and their correlation with gastric cancer. Using the median value of serum folate computed among the overall population as the cutoff value, the associations between serum folate and gastric cancer in all cases and different age and gender subgroups were analyzed by multivariate logistic regression analysis. In the patient cohort of gastric cancer, receiver-operating characteristic analyses were performed to calculate the best cutoff values of serum folate, and the associations between serum folate levels and clinicopathological features were further analyzed by multivariate regression analysis. Survival analyses were conducted using the Cox proportional hazards model.RESULTS: The mean serum folate level was significantly lower in gastric cancer patients than that in controls (3.71 ± 0.30 ng/mL vs 8.00 ± 0.54 ng/mL, P < 0.01), and folate levels were consistently lower in gastric cancer patients regardless of age and gender (all P < 0.01). Using the median serum folate value as the cutoff value, low serum folate was significantly associated with gastric cancer risk in the whole population (OR = 19.77, 95%CI: 10.54-37.06, P < 0.001) and all strata (age < 60 years OR = 17.39, 95%CI: 7.28-41.54, age ≥ 60 years (OR = 21.67, 95%CI: 8.27-56.80), males (OR = 17.95, 95%CI: 7.93-40.62), and females (OR = 20.95, 95%CI: 7.66-57.31); all P < 0.001. In the patient cohort of gastric cancer, the respective cutoff values showed that low serum folate levels were significantly associated with serosal invasion (OR = 2.54, 95%CI: 1.23-5.23), lymphatic invasion (OR = 2.23, 95%CI: 1.17-4.26), and liver metastasis (OR = 6.67, 95%CI: 1.28-34.91) of gastric cancer (all P < 0.05). Serum folate level below 1.90 ng/mL was associated with poor patient survival (HR = 1.84, 95%CI: 1.04-3.27, P < 0.05) in univariate analysis.CONCLUSION: Lower serum folate levels were significantly associated with gastric cancer development and invasive phenotypes. The role of folate depletion in gastric cancer invasion warrants further study.     

Cost-effectiveness of colorectal cancer screening: comparison of community-based flexible sigmoidoscopy with fecal occult blood testing and colonoscopy

BACKGROUND AND AIMS: To determine the cost-effectiveness of screening for colorectal cancer using flexible sigmoidoscopy once every 10 years, compared with annual and biennial rehydrated Hemoccult fecal occult blood testing and colonoscopy once every 10 years, or no screening. METHODS: A Markov model was developed in order to simulate the progression of a cohort of asymptomatic, average-risk individuals aged 55-64 years who were moving through a defined series of states towards death. The main outcome measures were: cases of colorectal cancer averted, colorectal cancer deaths averted, and cost per life-year saved. RESULTS: Colonoscopy averted the greatest number of cases of colorectal cancer (35%), followed by flexible sigmoidoscopy (25%), and annual (24%) and biennial (14%) fecal occult blood testing. Colonoscopy averted the greatest number of deaths from colorectal cancer (31%), followed by annual fecal occult blood testing (29%), flexible sigmoidoscopy (21%) and biennial fecal occult blood testing (19%). Flexible sigmoidoscopy was the most efficient in terms of cost per life-year saved (16,801 Australian dollars), followed by colonoscopy (19,285 Australian dollars), biennial (41,183 Australian dollars), and annual (46,900 Australian dollars) fecal occult blood testing. CONCLUSIONS: Flexible sigmoidoscopy and colonoscopy are cost-effective strategies for reducing the disease burden of colorectal cancer.     

Colorectal cancer and folate

Nutritional factors are important contributors to colorectal cancer prevention. There is some evidence to suggest that a high dietary folate intake is associated with a reduced risk of colorectal cancer. Folate, which is found in green leafy vegetables, is involved in C1 group transfer and contributes to purin and thymi-dilate synthesis as well as to DNA methylation. Alterations in gene expression and DNA damage are discussed to result from low folate levels and might be associated with an elevated risk of colorectal malignancies. This hypothesis can be supported by the finding that a common polymorphism in the methylentetrahydrofolate reductase gene enhances the risk of colorectal cancer when folate status is low. Both retrospective and prospective epidemiologic studies confirm the observation that a high intake of folate correlates with a lower risk of colorectal cancer. There is also evidence from epidemiological studies that diets which are low in methyl donors, such as low contents of folate and/or methionine combined with relatively high alcohol consumption, even enhance the risk of colorectal cancer. A small number of intervention trials provide first evidence that folate intakes far above recommended dietary allowances might influence possible biomarkers of colorectal tumours.     

The detection of colorectal cancer at an asymptomatic stage by screening is useful

BACKGROUND/AIMS: The validity of mass screening using fecal occult blood testing remains controversial. In addition, no controlled clinical study has yet been performed to show the usefulness of sigmoidoscopy. The purpose of the present study was to compare the surgical results achieved in asymptomatic patients with colorectal cancer detected by screening with those in symptomatic individuals. METHODOLOGY: A total of 285 patients underwent a surgical resection of colorectal cancer between 1991 and 1997 at our institution. Among them, 233 patients had complaints related to cancer at the time of diagnosis. In contrast, 52 were asymptomatic. In those 52 patients, colorectal cancer had been suspected based on routine screening including fecal occult blood testing, colonoscopy and/or elevated serum levels of carcinoembryonic antigen. RESULTS: Early stage of colorectal cancer was more frequently seen in asymptomatic patients than in symptomatic patients P < 0.01. The survival rates for asymptomatic patients was also superior to those of symptomatic patients P < 0.05. CONCLUSIONS: Screening using fecal occult blood testing, colonoscopy and tumor markers is thus considered to be beneficial for the early detection of colorectal carcinoma, which also tends to demonstrate good surgical results.