Aurora-A and Cyclin D1 polymorphisms and the age of onset of colorectal cancer in hereditary nonpolyposis colorectal cancer

Polymorphisms in the 2 cell-cycle control genes Aurora A and Cyclin D1 have previously been associated with changes in the age of onset of colorectal cancer in persons harboring germline mutations in DNA mismatch repair genes associated with hereditary nonpolyposis colorectal cancer (HNPCC). In this report, we have genotyped 312 individuals, who all harbored confirmed causative mutations in either hMSH2 or hMLH1, for 2 polymorphisms, one in Aurora A (T91A) and the other in Cyclin D1 (G870A). The results reveal that the previous association with the Aurora A polymorphism could not be confirmed in our larger group of HNPCC patients. The Cyclin D1 polymorphism, however, was associated with a significant difference in the age of disease onset on patients harboring hMSH2 mutations, which was not observed in hMLH1 mutation carriers. A combined analysis of the Aurora A and Cyclin D1 polymorphisms did not reveal any obvious association. In conclusion, it appears that the polymorphic variant of Aurora A does not appear to be associated with variation in colorectal cancer risk in HNPCC, whereas there is a more complex relationship between the Cyclin D1 polymorphism and disease risk in HNPCC.     

Clinical manifestations in patients with hereditary nonpolyposis colorectal cancer

The clinical manifestations of 1,042 Japanese patients with nonpolyposis colorectal cancer who underwent a resection between 1972 and 1992 at the National Kyushu Cancer Center were examined. Hereditary nonpolyposis colorectal cancer (HNPCC) was found in 39 (3.7%) patients. Some characteristic findings in HNPCC cases included early age of onset, a preponderance of right colon cancers, an increased frequency of colorectal cancers, and a favorable survival. Metachronous (postoperative) colorectal cancers developed significantly more often in cases with HNPCC than in those without (12.8% vs. 1.8%, P = 0.0001). Metachronous (postoperative) extracolonic cancers tended to develop more often in cases with HNPCC than in those without (10.2% vs. 3.5%, P = 0.053). In cases with HNPCC, the mean interval between the initial surgery and the diagnosis of the second cancer was 61 months (range; 12–153 months). These findings thus indicate the importance of routine and long-term follow-up to identify any second lesions, especially in patients with HNPCC. © 1996 Wiley-Liss, Inc.     

Surveillance for endometrial cancer in hereditary nonpolyposis colorectal cancer syndrome

The estimated lifetime risk for endometrial carcinoma (EC) in hereditary nonpolyposis colorectal cancer syndrome (HNPCC) is 32-60%, thus supporting surveillance. The survival rate of EC patients is, however, favourable questioning the need for surveillance. Yet, the effectiveness of gynecological surveillance remains to be shown. The 2 previously published studies were based on transvaginal ultrasound (TVUS) alone. Intrauterine biopsy has not been tested in surveillance for EC in HNPCC families. The effect of gynecological surveillance was evaluated among 175 Finnish mutation carriers. During 759 person years at risk, there were 503 surveillance visits including TVUS and intrauterine biopsy of endometrium at 94% and 74% of the visits, respectively. EC occurred in 14 cases, 11 of which were diagnosed by surveillance, 8 by intrauterine biopsies. TVUS indicated only 4 EC patients but missed 6 other cases. Intrauterine sampling detected 14 additional cases of potentially premalignant hyperplasia. The stage distribution and survival tended to be more favorable in the 14 EC cases of the surveilled group (no deaths) than in the group of 83 symptomatic mutation carriers of whom 6 died of EC, but with no statistical significance. Four cases of ovarian cancer occurred but none was detected by surveillance in TVUS examinations. In conclusion, EC surveillance in HNPCC seems more effective with endometrial biopsies than with TVUS alone. A definite improvement in survival remains to be shown. The detection of early cancer stages and premalignant lesions offers the opportunity to avoid extensive adjuvant treatment.     

Association between Aurora-A kinase polymorphisms and age of onset of hereditary nonpolyposis colorectal cancer in a Caucasian population

Aurora-A kinase is considered a potential cancer susceptibility gene that encodes a centrosome-associated, cell cycle-regulated serine/threonine kinase. We studied two single nucleotide polymorphisms (SNP) in the coding region of Aurora-A, 91T-to-A (F31I) and 169G-to-A (V57I). We studied the influence of these two polymorphisms on age of onset of hereditary nonpolyposis colorectal cancer (HNPCC). Genotyping of the Aurora-A polymorphisms was carried out on 125 Caucasian with mismatch repair (MMR) gene mutations with real-time pyrophosphate DNA sequencing. For the 91T-to-A polymorphism, we found that patients with HNPCC who were homozygous for the wild-type allele developed colorectal cancer (CRC) 7 years earlier than patients who were homozygous or heterozygous for the mutant allele. The169G-to-A polymorphism did not have a significant influence on risk for HNPCC. However, when we did haplotype analysis for these two polymorphisms, the 91A-169G haplotype was associated with protection from HNPCC at an earlier age.     

Survival after adjuvant 5-FU treatment for stage III colon cancer in hereditary nonpolyposis colorectal cancer

In vitro studies suggest that a deficient mismatch repair (MMR) system reduces 5-Fluorouracil cytotoxicity. Colon cancer (CC) in hereditary nonpolyposis colorectal cancer (HNPCC) is due to a dysfunctioning MMR gene that leads to microsatellite instability (MSI). Clinical studies on the efficacy of 5-Fluorouracil (5-FU) in MSI high tumours are contradictory. In a retrospective study, we compared the survival of subjects with stage III CC from HNPCC families that were treated with and without adjuvant 5-FU. The Dutch HNPCC family registry was used. Information on adjuvant chemotherapy for stage III CC was obtained from subjects of families with a mutation and/or who fulfilled the AMS criteria or who were strongly suspicious for HNPCC. CC specific survival was calculated. Observation time was measured either until the date of death, date of a second primary CC or until the closing date of the study, i.e., June 1, 2001. Statistical analysis was done by Kaplan-Meier survival analysis. A total of 92 subjects with stage III CC were included. Twenty-eight of them (17 males) had adjuvant treatment with 5-FU. The median follow-up was 4 (range: 1-17) years; 8 subjects died of CC. The 5-year survival was 70% (95% Cl: 49-90). Sixty-four subjects (36 males) did not have adjuvant therapy. Their median follow-up was 6 (range: 0-23) years. Twenty of them died of CC. The 5-year survival in this group was also 70% (95% Cl: 59-83). To date, the selection of patients with CC for 5-FU treatment is based on the stage rather than the biology of the tumour. In our study, the 5-year survival of subjects treated with and without adjuvant 5-FU did not differ. Further studies are necessary to elucidate the role of MSI in 5-FU treatment of MSI-H tumours in HNPCC.     

The added value of PMS2 immunostaining in the diagnosis of hereditary nonpolyposis colorectal cancer

Identification and characterization of the genetic background in patients with the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome is important since control programmes can in a cost-effective manner prevent cancer development in high-risk individuals. HNPCC is caused by germline mismatch repair (MMR) gene mutations and the genetic analysis of HNPCC therefore includes assessment of microsatellite instability (MSI) and immunohistochemical MMR protein expression in the tumor tissue. MSI is found in >95% of the HNPCC-associated tumors and immunostaining using antibodies against the MMR proteins MLH1, MSH2, and MSH6 has been found to correctly pinpoint the affected gene in about 90% of the cases. The PMS2 antibody was the most recently developed and we have in a clinical material assessed the added value of PMS2 immunostaining in 213 patients with suspected hereditary colorectal cancer. All 119 MSS tumors showed retained expression for all four antibodies and PMS2 did thus not identify any underlying MMR defect in these cases. However, PMS2 immunostaining contributed to the characterization of the MMR defect in a subset of the MSI tumors. Concomitant loss of MLH1 and PMS2, which functionally interact in the MutLα complex, was found in 98% of the tumors from patients with germline MLH1 mutations. Among the 12 MSI-high tumors with retained expression of MLH1, MSH2 and MSH6, 8 tumors showed loss of PMS2 staining, and mutations in MLH1 were identified in 2 and mutations in PMS2 in 3 of these individuals. In summary, isolated loss of PMS2 was found in 8% of the MSI-high tumors in our series, including 8/12 previously unexplained MSI-high tumors, in which mutations either in MLH1 or in PMS2 were identified in five cases.     

Heterozygosity for the Cys282Tyr mutation in the HFE gene and the risk of colorectal cancer (Netherlands)

Background & Aims: Heterozygosity for the Cys282Tyr transition in the HFE-gene is associated with slightly increased iron levels and may therefore be a potential risk factor for colorectal cancer. Methods: We studied the relationship between Cys282Tyr-heterozygosity and colorectal cancer using a case–control design. The 240 colorectal cancer cases and 635 controls in our study were derived from a prospective cohort study of 12,242 postmenopausal women, who were invited for an experimental breast cancer screening program in Utrecht, the Netherlands. The women were age 51–69 at time of inclusion and were followed for a period of 20 years. HFE genotyping was performed by PCR and allele-specific oligonucleotide (ASO) hybridization. Results: The risk of colorectal cancer was higher for women who were heterozygous for the Cys282Tyr mutation, than for those who were Cys282Tyr-wildtypes, although this was not statistically significant (Age-adjusted OR = 1.2, 95% CI: 0.6–2.2). Cys282Tyr-heterozygotes who smoked seemed to be at higher risk of colorectal cancer, although the p-value for interaction was not significant (p-value 0.42). Conclusions: The Cys282Tyr mutation is not associated with an increased risk for colorectal cancer in postmenopausal women, although in combination with smoking a slightly increased risk cannot be excluded.     

N-acetyltransferase (NAT) 2 acetylator status and age of onset in patients with hereditary nonpolyposis colorectal cancer (HNPCC)

N-acetyltransferase (NAT) 2 is an essential polymorphic enzyme involved in the metabolism of various xenobiotics, including potential carcinogens. The individual differences in the NAT2 metabolic capacity are caused by allelic variants of the NAT2 gene which are determined by a pattern of single nucleotide polymorphisms (SNPs) resulting in slow (SA), intermediate (IA) or rapid acetylator (RA) phenotypes. Highly penetrant germline mutations in mismatch repair (MMR) genes are the cause of the disease in hereditary nonpolyposis colorectal cancer (HNPCC). There is no strict correlation between the type of germline mutation in MMR genes and the HNPCC phenotype, but age of tumor onset (AO) in HNPCC has been associated at least in part with different variants in apoptosis-related genes. To clarify the potential modifying role of the NAT2 acetylator status in HNPCC, we performed a multicenter study in 226 individuals with colorectal cancer carrying exclusively pathogenic germline mutations in MSH2 or MLH1. We did not observe any significant difference in the NAT2 acetylator status frequency between HNPCC patients and 107 healthy controls (P=0.156), and between MLH1 and MSH2 mutation carriers (P=0.198). Multivariate Cox regression analysis revealed that male patients had a significantly increased risk to develop CRC compared to females during any interval (P=0.043), while the NAT2 acetylator status (P=0.447) and the mutated gene (MLH1 or MSH2) (P=0.236) were not risk factors for AO. The median AO in HNPCC patients was 39 years in patients with RA as well as with SA status (P=0.347). In MLH1 mutation carriers, the median AO was 38 years in RA and 36 years in SA status patients (P=0.901), whereas in MSH2 mutation carriers, the median AO was 39 years in RA and 42 years in SA status patients (P=0.163). Log-rank test revealed a significantly lower age of CRC onset in male compared to female HNPCC patients (P=0.0442). These data do not support the hypothesis that the NAT2 acetylatorship acts as a modifying factor on AO in HNPCC-associated CRC.     

Male breast cancer in the hereditary nonpolyposis colorectal cancer syndrome

A male member of a large HNPCC kindred, affected by primary malignancies of the breast and colon, was identified. This individual was found to harbor a germline mutation of the MLH1 mismatch repair gene previously shown to segregate with disease in this kindred. The breast tumor exhibited somatic reduction to homozygosity for the MLH1 mutation, and microsatellite instability was evident in the breast tumor. We conclude that hereditary male breast cancer can occur as an integral tumor in the HNPCC syndrome.     

遗传性非腺瘤病性结直肠癌的诊治进展

遗传性非腺瘤病性结直肠癌（HNPCC）是一种常染色体显性遗传的综合症,占总的结直肠癌的56%--10%。该病由错配修复基因缺陷造成,肿瘤表现出高度的微卫星不稳。临床上辨别HNPCC患者对诊断和治疗以及监测HNPCC家庭成员发病有指导意义。     

Genetic testing among high-risk individuals in families with hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC) is frequently associated with constitutional mutations in a class of genes involved in DNA mismatch repair. We identified 32 kindreds, with germline mutations in one of three genes hMSH2, hMLH1 or hMSH6. In this study, we purposed to evaluate how many high-risk individuals in each family underwent genetic testing: moreover, we assessed how many mutation-positive unaffected individuals accepted colonoscopic surveillance and the main findings of the recommended follow-up. Families were identified through a population-based registry, or referred from other centres. Members of the families were invited for an education session with two members of the staff. When a kindred was consistent with HNPCC, neoplastic tissues were examined for microsatellite instability (MSI) and immunohistochemical expression of MSH2, MLH1 and MSH6 proteins. Moreover, constitutional mutations were searched by SSCP or direct sequencing of the whole genomic region. Of the 164 subjects assessed by genetic testing, 89 were gene carriers (66 affected - that is, with HNPCC-related cancer diagnosis - and 23 unaffected) and 75 tested negative. Among the 23 unaffected gene carriers, 18 (78.3%) underwent colonoscopy and four declined. On a total of 292 first degree at risk of cancer, 194 (66.4%) did not undergo genetic testing. The main reasons for this were: (a) difficulty to reach family members at risk, (b) lack of collaboration, (c) lack of interest in preventive medicine or 'fatalistic' attitude towards cancer occurrence. The number of colorectal lesions detected at endoscopy in gene carriers was significantly (P<0.01) higher than in controls (noncarriers). We conclude that a large fraction of high-risk individuals in mutation-positive HNPCC families does not undergo genetic testing, despite the benefits of molecular screening and endoscopic surveillance. This clearly indicates that there are still barriers to genetic testing in HNPCC, and that we are unable to provide adequate protection against cancer development in these families.     

IGF1 is a modifier of disease risk in hereditary non-polyposis colorectal cancer

Patients diagnosed with HNPCC harbouring a confirmed germline mutation in DNA mismatch repair (MMR) genes have an 80% lifetime risk of developing an epithelial malignancy. There is, however, considerable variation in the age of disease onset in these patients. Insulin-like growth factor-I (IGFI) has been implicated in colorectal cancer (CRC), and elevated plasma IGFI levels are associated with both sporadic and hereditary CRC risk. In this study, we further investigate the cytosine-adenine (CA) dinucleotide repeat polymorphism located near the promoter region of IGF1 and its relation to early onset CRC risk in 443 Australian and Polish MMR gene mutation carriers using DNA sequencing, Kaplan-Meier survival curves and Cox proportional hazard regression analysis. A significantly smaller number of IGF1 CA repeats was observed in the Polish patient population, which was associated with an earlier age of disease onset compared to the Australian patients. The threshold for the observed modifying effect was again shown to be in patients with 17 or less CA repeats compared to those with 18 or more. Furthermore, when MMR mutation group (i.e., MLH1 or MSH2), gender and family clustering were included in the final Cox model we observed a more robust trend for the role of the IGF1 CA repeat in predicting age of disease onset in HNPCC patients. In addition, this effect was shown to be equal in both MLH1 and MSH2 mutation carrier groups and not restricted to a particular MMR subgroup (p = 0.001). We conclude that the IGF1 CA repeat is an important modifier of disease onset in HNPCC and the first polymorphism to yield consistent results across different populations.     

Molecular genetic alteration and DNA ploidy in hereditary nonpolyposis colorectal cancer

Background To clarify the biologic characteristics of hereditary nonpolyposis colorectal cancer (HNPCC), an investigation was made of the association of this cancer with mutations of theTP53 (aliasp53) and K-ras genes, and with DNA ploidy. Methods Samples from 19 patients with HNPCC and from 56 patients with sporadic colorectal cancer were analyzed by polymerase chain reaction-single strand conformation polymorphism and flow cytometric analyses. Results Mutations of thep53 gene were found in 7 (32%) of 22 samples from HNPCC patients, and K-ras mutations were found in 8 (44%) of 18 samples from HNPCC patients. Aneuploidy was noted in 8 (44%) of 18 samples. Each incidence in HNPCC was similar to the corresponding incidence in the sporadic colorectal cancers. Conclusion The results of this investigation indicate that HNPCC shows no difference from sporadic colorectal cancer in terms ofp53 and K-ras alterations, or DNA ploidy.     

遗传性非息肉病性结直肠癌7个家系的临床分析

目的:总结遗传性非息肉病性结直肠癌(HNPCC)家系的临床特点,提高临床诊断和治疗水平。方法:收集7个HNPCC家系的病例资料,分析其发病特点并记录随访结果。结果:7个HNPCC家系共有癌症患者23例,肿瘤灶27处:大肠外瘤灶3处;大肠瘤灶24处,其中有13处位于脾曲近侧结肠,占54.1%。平均发病年龄为41.2岁,17例(73.5%)发病在50岁以前。1家系累及连续三代人、4家系累及连续两代人。多原发癌患者4例,其中3例为肠外癌。结论:HNPCC具有发病年龄轻、垂直传递、肠外癌发病率高、常见多原发癌、好发于右半结肠、病理分化较差的特点,但预后相对较好。     

Mutations of the 'minor' mismatch repair gene MSH6 in typical and atypical hereditary nonpolyposis colorectal cancer

Mutations of the mismatch repair (MMR) genes MLH1 and MSH2 are associated with hereditary nonpolyposis colorectal cancer (HNPCC), a highly penetrant autosomal dominant condition characterized by hypermutability of short tandemly repeated sequences in tumor DNA. Mutations of another MMR gene, MSH6, seem to be less common than MLH1 and MSH2 defects, and have been mostly observed in atypical HNPCC families, characterized by a weaker tumor family history, higher age at disease onset, and low degrees of microsatellite instability (MSI), predominantly involving mononucleotide runs. We have investigated the MSH6 gene sequence in the peripheral blood of 4 HNPCC and 20 atypical HNPCC probands. Two frameshift mutations within exon 4 were detected in 2 patients. One mutation was found in a proband from a typical HNPCC family, who had developed a colorectal cancer (CRC), a gastric cancer and a rectal adenoma. The CRC and the adenoma showed mild MSI limited to mononucleotide tracts, while the gastric carcinoma was microsatellite stable. The other mutation was detected in an atypical HNPCC proband, whose CRC showed widespread MSI involving both mono- and dinucleotide repeats. The phenotypic variability associated with MSH6 constitutional mutations represents a complicating factor for the optimization of strategies aimed at identifying candidates to MSH6 genetic testing.     

Absence of association between cyclin D1 (CCND1) G870A polymorphism and age of onset in hereditary nonpolyposis colorectal cancer

CCND1 encodes cyclin D1, which plays an important role in the G₁ to S phase transition of the cell cycle. A common polymorphism (c.G870A) increases alternate splicing. Hereditary nonpolyposis colorectal cancer (HNPCC) is caused by mutations in mismatch repair (MMR) genes, mainly MSH2 and MLH1, and shows a wide range in the age of its onset (AO), suggesting the existence of other modifying genetic factors. To date, two studies have investigated the association between CCND1 G/A variation and AO in HNPCC with contradictory results in 86 and 146 MMR mutation carriers, respectively. To clarify the role of the CCND1 G/A variation in HNPCC, we performed a study in 406 individuals carrying exclusively clear cut pathogenic mutations in MSH2 or MLH1. We did not observe a significant difference in genotype frequencies of affected and unaffected mutation carriers and healthy controls. A significant association between CCND1 genotypes and AO was found neither in the global comparison (log-rank, P=0.2981; Wilcoxon, P=0.2567) nor in a multivariate Cox regression analysis (hazard ratios 1.111, 95%CI 0.950–1.299, P=0.188 and 1.090, 95%CI 0.868–1.369, P=0.459 for the additive and dominant effect, respectively). We conclude, that the CCND1 G870A sequence variation is not a genetic modifier of the phenotype of HNPCC.     

中国人遗传性非息肉病性结直肠癌家系的临床表型分析

目的 分析中国人遗传性非息肉病性结直肠癌（HNPCC）家系的临床特征,并评价中国人HNPCC家系标准的临床应用价值。方法 收集符合中国人HNPCC家系标准的家系26个,与509例散发性大肠癌比较,分析其临床特点,26个家系中,8个同时符合Amsterdam标准,分入A组;另18个不符合Amsterdam标准,仅符合中国人HNPCC家系标准,分入B组,分析比较两组间临床特点。结果 26个家系中,大肠癌患者77例,发生同时或异时大肠癌7例（9．1％）,共发生大肠癌癌灶86个,部位明确的71个癌灶中,28个（39．4％）发生在近端结肠,51例（71．8％）患者发病年龄〈50岁,共发生肠外恶性肿瘤24个,其中胃癌9个（37．5％）,是最常见的类型。与散发性大肠癌相比,HNPCC家系具有平均发病年龄轻（P=0．000）、〈50岁者多见（P=0．000）、多原发癌比例高（P=0．015）等特征。与B组相比,A组平均每个家系发生大肠癌的例数明显多于B组（4．5：2．3,P=0．022）;而在平均发病年龄、肿瘤发生部位、多原发大肠癌发生情况、肠外恶性肿瘤谱等方面差异均无统计学意义。结论 （1）中国人HNPCC具有发病年龄轻、多原发大肠癌发生率高及肠外恶性肿瘤以胃癌多见的特点,（2）符合中国人HNPCC家系标准的家系与符合Amsterdam标准的家系具有相似的临床特征,而中国人HNPCC家系标准更适用于小型家系的诊断、同时体现了中国人的肿瘤谱特征。