遗传性非息肉性结直肠癌诊疗进展

遗传性结直肠癌在所有结直肠癌患者中大约占5％～10％,其中遗传性非息肉性结直肠癌（heredi-tary nonpolyposis colorectal cancer,HNPCC）也称Lynch综合征,是最常见的一种遗传性结直肠癌综合征,约占全部结直肠癌的1％～5％。HNPCC在我国并未引起足够的重视,常常漏诊。随着科学技术的进步以及分子遗传学的快速发展,我国的结直肠癌专家们也开始注意到HNPCC,正确认识HNPCC的发病特点、遗传学特征以及临床治疗方法对有效防治结直肠癌有十分重要的意义。     

DNA错配修复系统和微卫星不稳定性与结直肠癌

结直肠癌(CRC)是消化系统常见的恶性肿瘤之一。其发生发展涉及到一系列遗传学改变。已有大量的研究证实，微卫星不稳定性(MSI)存在于遗传性非息肉性结直肠癌(HNPCC)，部分散发性结直肠癌(SCRC)胃癌等当中，MSI是错配修复基因的异常造成的。DNA错配修复基因的突变可以解释90％以上的HNPCC，少部分的HNPCC肿瘤和散发性MSl 的肿瘤可由其他途径所致，比如基因的甲基化。     

遗传性非息肉病性结直肠癌8个家系临床及病理分析

目的分析遗传性非息肉病性结直肠癌（HNPCC）家系临床及病理特点。方法收集符合Amsterdam标准Ⅱ的8例HNPCC家系资料,绘制家系图谱。结果HNPCC发病率为1.59%,8个HNPCC家系总发病人数为31例,其中结直肠癌患者为25例,肠外相关肿瘤6例,8例先证者中6例为女性,2例为男性,4例发病年龄小于40岁,发病部位位于右半结肠为2例,左半结肠3例,直肠3例,组织学分型以中至低分化腺癌为主;均未出现淋巴结及远处转移;8例先证者错配修复（MMR）蛋白表达异常的为5例。结论HNPCC先证者发病年龄轻,组织学分型较好,家系成员发病率高,对其家族成员进行定期检查和及时治疗将能有效地预防其发生并降低死亡率;MMR基因突变检测对提高HNPCC的诊断起重要作用。     

遗传性非息肉病性结直肠癌分子病理学特点与临床应用

近年来结直肠癌发生率仍呈上升趋势,在发达国家及国内一些发达城市和地区,结直肠癌已成为主要致死性病因之一.随着分子生物学及遗传学的发展,近来人们在分子水平及遗传学角度对结直肠癌的发生机制、病因、临床特点及应用等方面进行了广泛深入地研究,尤其对遗传性非息肉病性结直肠癌(hereditary nonpolyposis colorectal cancer,HNPCC)的分子遗传学研究使利用HNPCC分子病理学特征前瞻性地筛选HNPCC家系成为可能,该病的临床处理模式也因此发生了较大改观[1].     

中国部分地区结直肠癌遗传易感性与遗传性非息肉病性结直肠癌流行状况分析

目的了解结直肠癌患者的遗传易感性与结直肠癌人群中遗传性非息肉病性结直肠癌（HNPCC）的流行状况。方法结直肠癌患者分为两部分：第一部分为作者连续调查的结直肠癌患者,第二部分来源于近年来公开发表的有关中国人HNPCC发病率的文献。采用阿姆斯特丹标准Ⅰ、Ⅱ和日本标准等诊断HNPCC。结果17．2％的患者具有恶性肿瘤遗传易感性,5．2％的患者具有结直肠癌遗传易感性;多原发恶性肿瘤、多原发结直肠癌等分别占13．1％、10．1％;多原发恶性肿瘤（P=0．001）、多原发结直肠癌（P=0．000）等的发生均与恶性肿瘤家族史相关;低龄结直肠癌（≤50岁）患者占21．4％,其发生与恶性肿瘤家族史（P=0．000）、结直肠癌家族史（P=0．000）等均呈密切相关;符合阿姆斯特丹标准Ⅰ、Ⅱ和日本标准等HNPCC的检出率分别为1．24％、2．15％和2．93％,南、北地区间的差异没有统计学意义（P〉0．05）。结论恶性肿瘤家族史、多原发恶性肿瘤和低龄结直肠癌（≤50岁）是3种恶性肿瘤及结直肠癌遗传易感性的临床标志。多原发恶性肿瘤、低龄结直肠癌等与恶性肿瘤家族史相关。我国HNPCC的流行率与西方国家相当。     

中国人遗传性非息肉病性结直肠癌相关肿瘤谱及累计发病风险

目的:探讨中国人遗传性非息肉病性结直肠癌(HNPCC)相关肿瘤谱和累计发病风险,为制定HNPCC诊治方案提供依据.方法:随访31个HNPCC家系中167例肿瘤患者,以Kaplan-Meier生存曲线法估计各种肿瘤发生比例和累计发病风险.结果:167例HNPCC相关肿瘤患者的首发肿瘤中,结直肠癌135例(80.8%),胃癌10例(6.0%),子宫内膜癌8例(4.8%),卵巢癌3例(1.8%),膀胱癌、乳腺癌、肺癌和脑胶质瘤各2例(分别占1.2%),肝癌、胰腺癌和胆囊癌各1例(分别占0.6%).70岁时,大肠癌发生累计发病风险为93.3%,肠外肿瘤发生累计发病风险为56.1%.结论:中国人HNPCC肿瘤谱中,胃癌发生率较高;40～60岁大肠癌发生风险最大,50岁后肠外肿瘤发生风险明显增加.     

无hMLH1/hMSH2生殖系突变的遗传性非息肉病性结直肠癌3家系报道

目的:考察遗传性非息肉病性结直肠癌(HNPCC)家系hMLH1/hMSH2生殖系突变的情况.方法:选择13个符合Amsterdam标准的HNPCC家系中的先证者,利用DNA 测序检测hMLH1/hMSH2基因突变情况.对其中不携带hMLH1/hMSH2生殖系突变的HNPCC 家系,利用免疫组化检测hMLH1/hMSH2基因表达、PCR-SSCP检测先证者肿瘤组织的微卫星不稳定性(MSI).结果:13个HNPCC家系的先证者中有3例检测不到hMLH1/hMSH2的生殖系突变.3例无hMLH1/hMSH2突变的先证者中,肿瘤组织的微卫星不稳定检测均为MSI-H,免疫组化检测hMLH1/hMSH2基因表达正常.结论:3个严格符合Amsterdam标准的HNPCC家系中未发现hMLH1/hMSH2基因系突变,提示可能存在其他基因突变导致该3个家系HNPCC肿瘤发生.     

TGF-β/Smad信号通路及Smad4、p15在结直肠癌中的研究进展

结直肠癌是消化系统常见肿瘤之一,其发病率和病死率较高。转化生长因子-β（transforming growth factor-β,TGF-β）/Smad（small mothers against decapentaplegic）信号通路可调控肿瘤细胞的增殖、分化、浸润、迁移,与结直肠癌的发生发展过程相关。研究表明,Smad4和p15是TGF-β/Smad信号通路的关键效应因子,与肿瘤的侵袭、进展及预后密切相关。本文对TGF-β/Smad信号通路及Smad4、p15在结直肠癌中的最新研究进展进行综述。     

微卫星不稳定技术能够检测Lynch综合征

新近发表于Int J Cancer的一篇报道显示,年轻的结直肠癌患者用微卫星不稳定（microsatellite instability,MSI）技术能够检测出是否患有Lynch综合征。又称为遗传性非息肉性结直肠癌（HNPCC）。     

遗传性非息肉病性大肠癌30例临床病理特点与诊治分析

目的：探讨遗传性非息肉病性大肠癌（hereditary nonpolyposis colorectal cancer,HNPCC）的临床病理及分子病理特征,提高对该病的认识和诊疗水平。方法：回顾性分析中南大学湘雅医院普通外科诊治的30例HNPCC病人,以同期在该院治疗的散发性结直肠癌25例为对照组。比较其发病年龄、肿瘤部位、病理类型、治疗方法及预后。采用免疫组织化学检测两组病人错配修复基因（mismatch repair genes,MMR）MLH1和 MSH2 表达缺失率。结果：与对照组相比,HNPCC组的发病年龄早,近段大肠癌比例高,易于合并多发癌,肿瘤高分化类型所占比例高（P＜0.05）。MLH1和 MSH2 表达缺失率高于对照组（P＜0.05）。HNPCC组中1/3的病人接受了大肠次全切除术,预后与散发大肠癌相当（P＞0.05）。结论：HNPCC具有发病早,易合并多发癌的特点,结合MMR的检测可提高诊断的准确率。彻底手术和密切随访可取得好的效果。     

青年大肠癌微卫星不稳定和hMLH1/hMSH2表达缺失在遗传性非息肉病性大肠癌初筛中的应用

目的 探讨青年大肠癌中微卫星不稳定发生率和hMLH1/hMSH2表达缺失率及其在遗传性非息肉病性大肠癌初步筛查中的作用.方法 对73例中国南方青年大肠癌患者(年龄≤40岁)进行微卫星不稳定和hMLH1/hMSH2蛋白免疫组化检测.结果 微卫星不稳定性发生率为56.16%,hMLH1和/或hMSH2表达缺失率为49.32%,二者皆随患者发病年龄的降低而迅速增加;二者对阳性病例的检出率相似.结论 中国人青年大肠癌DNA错配修复基因缺陷为频发事件,运用微卫星不稳定分析和hMLH1/hMSH2蛋白免疫组化检测可在青年大肠癌有效地进行HNPCC患者及家系的初步筛查.     

遗传性非息肉病性结直肠癌中COX-2的表达及与MMR基因表达的分析

目的研究遗传性非息肉病性结直肠癌（HNPCC）中环氧合酶2（COX-2）的表达及与错配修复基因（MMR）的关系。方法选择2008年5月~2011年10月19个家系的家族遗传性非息肉病性大肠癌20例;选择同期本院收治的散发性大肠癌23例为对照组,采用免疫组化及PCR技术检测两组患者COX-2表达及MMR基因表达情况。结果 HNPCC大肠癌中COX-2高表达率为40.0%,散发性大肠癌中COX-2的高表达率为91.3%,两组比较差异有统计学意义（χ2=10.172,P〈0.05）。HNPCC大肠癌中MMR表达缺失率为70%,散发性大肠癌中MMR表达缺失率为13%,两组比较差异有统计学意义（χ2=9.872,P〈0.05）。MMR表达缺失的遗传性大肠癌及散发性大肠癌COX-2高表达率（21.4%、66.7%）均明显低于MMR阳性表达者（83.3%、95.0%）,差异有统计学意义（χ2=7.357、5.039,P〈0.05）。相关性分析显示,HNPCC大肠癌MMR表达缺失率与COX-2低表达率呈正相关（r=1.176,P〈0.05）,散发性大肠癌患者中,MMR表达率与COX-2高表达率呈正相关（r=1.869,P〈0.05）。结论遗传性非息肉病性结直肠癌中COX-2的表达较散发性大肠癌减低,MMR基因表达缺失率增高,COX-2、MMR基因表达情况在遗传性非息肉型结直肠癌的筛查及发病机制的研究中有重要意义。     

Clinical features and hMSH2/hMLH1 germ-line mutations in Chinese patients with hereditary nonpolyposis colorectal cancer

Background At least five mismatch repair （MMR） genes, including hMSH2, hMLH1, hPMS, hPMS2, and hMSH6/GTBP, are associated with hereditary nonpolyposis colorectal cancer （HNPCC）. More than 90% of families with HNPCC harbor the hMSH2and hMLH1 gene mutations. We have analyzed the clinical features of HNPCC among Chinese patients and report the results of screening for mutations in the hMSH2 and hMLH1 genes.
Methods The data concerning gender, site of colorectal cancer （CRC）, age at diagnosis, history of synchronous and/or metachronous colorectal cancer, instance of extracolonic cancers, and histopathology of tumors for 126 patients from 28 independent families with HNPCC were collected. Fifteen of the families met the Amsterdam I criteria, and 13 met the Japanese clinical criteria for diagnosis. Genomic DNA was extracted from the peripheral lymphocytes. Polymerase chain reaction （PCR） and denaturing high-performance liquid chromatography （DHPLC） were used to screen the coding region of the hMSH2 and hMLH1 genes. Samples showing abnormal DHPLC profiles were sequenced.
Results One hundred and seventy malignant neoplasms were found in the 126 patients, of whom 23 had multiple cancers. Ninety-eight of the patients （77.8%） had colorectal cancers, with an average age at onset of 45.9 years and a right-sided predominance. Eight hMSH2 or hMLH1 gene sequence variations were found in 12 families, and a germ-line G204X nonsense mutation in the third exon of hMSH2 was found, representing the first mutation in an MMR gene ever found in people of Chinese Mongolian ethnicity.
Conclusions HNPCC is a typical autosomally dominant hereditary disease, characterized by early onset, a predominance of proximal colorectal cancer, and multiple synchronous and metachronous colorectal cancers. DHPLC is a powerful tool for detecting mutations in the hMSH2 and hMLH1 genes, Mutations in the first nine exons of the hMLH1 gene were more common in Chinese patients.     

Novel hMLH1 and hMSH2 germline mutations in African Americans with colorectal cancer.

CONTEXT: Germline mutations of the DNA mismatch repair (MMR) genes hMLH1 and hMSH2 have been shown to cosegregate with the colorectal cancer phenotype in multiple hereditary nonpolyposis colorectal cancer (HNPCC) pedigrees. However, the frequency of these mutations among African American patients with colorectal cancer is unknown. OBJECTIVE: To investigate the frequency of germline alterations of the DNA MMR genes hMLH1 and hMSH2 among African Americans affected by HNPCC and early-age onset colorectal cancer. DESIGN, SETTING, AND PATIENTS: Forty unrelated African American HNPCC and early-age onset colorectal cancer patients (8 women, 3 men) were identified from the cancer registry at a National Cancer Institute-designated referral center, 11 of whom were available for and agreed to study participation from January 1997 to February 1998. The mean age of the subjects was 44 years. An additional 50 age- and sex-matched African Americans without personal or family history of colorectal, endometrial, ovarian, urinary tract, or upper gastrointestinal tract malignancy were also studied as a polymorphism control population. In all subjects, genomic DNA was amplified by polymerase chain reaction for all hMLH1 and hMSH2 exons and screened using single-strand conformation polymorphism (SSCP) analysis. Samples demonstrating significant SSCP shifts underwent automated nucleotide sequencing analysis. MAIN OUTCOME MEASURE: Frequency of hMLH1 and hMSH2 germline alterations in the affected and control subjects. RESULTS: Germline hMLH1 and hMSH2 mutations were detected in 3 (27%) of the African American colorectal cancer probands studied. Each mutation was novel. Two hMLH1 (an A-->T transversion at codon 26 and a GG-->AT substitution across codons 177 and 178) mutations and 1 hMSH2 mutation (a C-->T transition at codon 389) were identified in 3 female study subjects. Six other hMLH1 and hMSH2 alterations were detected but were presumed to be polymorphisms. Neither missense mutation (at codons 26 and 389) was detected in the control population. CONCLUSIONS: The results of our analysis support an association between the 3 mutations reported and predisposition to colorectal cancer. Further studies are needed to define DNA MMR gene-associated colorectal cancer in African Americans, an understudied population at increased risk of fatal colorectal cancer.     

22例微卫星DNA不稳定性大肠癌家系筛查结果分析

目的通过对既往已确认有微卫星不稳定的大肠癌患者的一级亲属随访调查研究,筛查遗传性非息肉病型大肠癌家系及早期遗传性非息肉病型大肠癌。方法选取已确认发现微卫星不稳定性（MSI）阳性大肠癌患者的一级亲属66例,进行随访。对尚未发生恶性肿瘤的63例无症状筛查对象行电子大肠镜检查,病变组织取病理活检,组织行HE染色,经病理医师诊断。结果66例筛选对象中已有3例发生恶性肿瘤,其他63例筛查对象中肠镜检查发现结肠绒毛状腺瘤1例,大肠息肉7例,遵循Amsterdam标准Ⅱ确诊4个HNPCC家系,其中结肠腺瘤病例出现在HNPCC家系中,属于癌前病变。结论具有遗传背景的MSI阳性的大肠癌患者的一级亲属有可能是遗传性非息肉性大肠癌的高危人群。对这些高危人群应进行定期的随访观察,有望早期发现HNPCC家系和早期遗传性非息肉病型大肠癌患者。     

遗传性非息肉病性大肠癌临床表型分析

目的 探讨我国遗传性非息肉病性大肠癌（HNPCC）患者的临床表型,为临床辨认HNPCC家系提供依据。方法 选择符合阿姆期特丹Ⅱ和日本的HNPCC标准的34个HNPCC家系为研究对象。研究发病的一般规律：（1）确诊时的年龄和性别;（2）绘出家系图;（3）肿瘤发生的部位（包括肠外癌）;（4）同时多原发结肠癌;（5）异时多原发结肠癌;（6）临床表现。结果 （1）34个家系中,18岁以上的家族成员共612人,确诊HNPCC的患者140例,女性47例,男性93例。（2）34个家系均为常染色体显性遗传。（3）确诊时的中位年龄为45．3岁,50岁以前发病者占62．1％,60岁以前发病者占87．1％;（4）154个原发癌灶中,肠外癌灶31个（20．1％）,其中胃癌占肠外癌的41．9％（13／31）,大肠癌灶123个（79．9％）。116例大肠癌患者中,右半结肠癌占66．4％（77／116）,左半结肠癌占33．6％（39／116）。（5）同时多原发癌5例,其中2例为3次多原发癌,3例为2次多原发癌;异时多原发癌6例（含肠外癌）。结论 本组HNPCC的临床特点为（1）发病年龄比西方患者更年轻;（2）右半结肠癌的比例高;（3）大肠癌的垂直传递特征突出;（4）肠外癌以胃癌比例较大;（5）同时原发癌和异时原发癌较多。     

修订Bethseda标准筛选遗传性非息肉病性结直肠癌患者的队列研究

目的研究修订Bethseda标准筛选遗传性非息肉病性结直肠癌（HNPCC）的价值及在结直肠癌中的构成比。方法对2004年8月至2005年12月进行手术治疗的连续110例患者建立队列、多重荧光聚合酶链反应方法检测肿瘤的微卫星不稳定（MSI）状态,对于MSI结直肠癌患者检测hMSH2、hMLH1和hMSH6基因种系突变。结果110例患者中共检出MSI结直肠癌患者23例（20．9％）。在23例MSI结直肠癌患者中,共发现病理性突变7个（30．4％）,占所有结直肠癌6．4％;其中hMSH6基因种系突变3个,hMSH2基因突变3个,hMLH1基因突变1个。结论以修订Bethesda标准,MSI结直肠癌检出率为20．9％,HNPCC检出率6．4％;在中国人错配修复基因种系突变中hMSH2和hMSH6错义突变比较多见。     

Expression of Cyclooxygenase-2 and Its Relationship with Mismatch Repair and Microsatellite Instability in Hereditary Nonpolyposis Colorectal Cancer

Objective To investigate cyclooxygenase-2 （COX-2） expression and its relationship with mismatch repair （MMR） protein expression and microsatellite instability （MSI） in hereditary nonpolyposis colorectal cancer （HNPCC）. Methods A total of 28 cases of colorectal adenoma and 14 cases of colorectal carcinoma were collected between July 2003 and July 2007 from 33 HNPCC families. Sporadic colorectal adenoma （n=32） and carcinoma patients （n=24） served as controls. With samples of tumor tissues and normal colonic mucosa collected from the patients, the protein expressions of COX-2 and MMR （hMLH1, hMSH2, and hMSH6） were examined with immunohistochemical assay. Frequency of MSI in five standard MSI loci BAT25, BAT26, D2S123, D5S346, and D17S250 were analyzed by means of polymerase chain reaction. Results The rate of COX-2 high-expression was 53.6% （15/28） and 42.9% （6/14） in HNPCC adenoma and carcinoma; 62.5% （20/32） and 91.7% （22/24） in sporadic adenoma and carcinoma, respectively. That rate was lower in HNPCC carcinoma than in sporadic carcinoma （P〈0.05）. MMR-deletion rate and percentage of high-frequency MSI （MSI-H） in HNPCC carcinoma were higher than those in sporadic colorectal carcinoma [both 71.4% （10/14） vs. 12.5% （3/24）, both P〈0.01]. Among the 10 MMR-deficient HNPCC carcinoma patients, COX-2 low-expression was observed in 8 cases （80.0%）, while COX-2 high-expression was observed in all of the 4 MMR-positive HNPCC carcinoma cases （P〈0.05）. In comparison to MMR positive HNPCC carcinoma, HNPCC adenoma, and sporadic carcinoma, COX-2 expression was significantly lower in corresponding MMR-deficient cases （all P〈0.05）. The rates of COX-2 low-expression in HNPCC adenoma, HNPCC carcinoma, and sporadic carcinoma with MSI-H were significantly higher than those in the cases with microsatellite stability （all P〈0.05）. Conclusion COX-2 is expressed at a low level in HNPCC carcinoma, different from the high COX-2 expression in sporadic carcinoma.