Clinical phenotype and prevalence of hereditary nonpolyposis colorectal cancer syndrome in Chinese population

Cancer genetic counseling communication with low-income Chinese immigrants

As genetics and genomics become part of mainstream medicine, these advances have the potential to either reduce or exacerbate health disparities. Relatively, little research has explored the quality of genetic counseling communication experienced by limited English proficiency patients, especially Chinese Americans. We observed and audio recorded genetic counseling appointments (n = 40) of low-income, limited English-proficient Chinese patients (n = 25) and conducted post-visit interviews (n = 17) using stimulated recall to examine patient understanding of the communication. Standard techniques based in grounded theory, including iterative data review and multiple coders, were used to analyze observation fieldnotes and interview transcripts and to identify these themes: (1) strong beliefs in environmental causes of cancer and skepticism about genetic causes, (2) willingness to undergo genetic testing despite skepticism of hereditary cause of cancer, (3) misunderstanding of key information needed to make informed decisions about testing and screening/prevention options, (4) variable quality of medical interpretation, and (5) selective family communication about cancer and genetic counseling and testing. Together, these themes describe substantial gaps in communication and identify the need for genetic counseling techniques and skills that enable counselors to communicate more effectively across language, literacy, and culture. Understanding the mechanisms of inheritance and the implications of genetic test results can be challenging for anyone, and it is exceptionally daunting for those who have limited English proficiency and/or low literacy. For Chinese immigrant patients to reap the full benefits of genetic counseling and testing, effective communication is essential. Research on interventions to improve communication is needed to ensure that disparities do not widen as genomic medicine reaches a more diverse population.

Molecular Subtypes of Colorectal Cancer and Their Clinicopathologic Features, With an Emphasis on the Serrated Neoplasia Pathway

CONTEXT

-Colorectal cancer is a heterogeneous disease entity with 3 molecular carcinogenesis pathways and 2 morphologic multistep pathways. Right-sided colon cancers and left-sided colon and rectal cancers exhibit differences in their incidence rates according to geographic region, age, and sex. A linear tendency toward increasing frequencies of microsatellite instability-high or CpG island methylator phenotype-high cancers in subsites along the bowel from the rectum to the cecum or the ascending colon accounts for the differences in tumor phenotypes associated with these subsites. The molecular subtypes of colorectal cancers exhibit different responses to adjuvant therapy, which might be responsible for differences in subtype-specific survival.

OBJECTIVES

-To review the clinicopathologic and molecular features of the molecular subtypes of colorectal cancer generated by combined CpG island methylator phenotype and microsatellite statuses, to integrate these features with the most recent findings in the context of the prognostic implications of molecular subtypes, and to emphasize the necessity of developing molecular markers that enable the identification of adenocarcinomas involving the serrated neoplasia pathway.

DATA SOURCES

-Based on the authors' own experimental data and a review of the pertinent literature.

CONCLUSIONS

-Because colorectal cancers arise from 2 different morphologic multistep carcinogenesis pathways with varying contributions from 3 different molecular carcinogenesis pathways, colorectal cancer is a heterogeneous and complex disease. Thus, molecular subtyping of colorectal cancers is an important approach to characterizing their heterogeneity with respect to not only prognosis and therapeutic response but also biology and natural history.

Familial adenomatous polyposis in China

Familial adenomatous polyposis (FAP) is an autosomal dominant disease with a poor prognosis, and has been studied by clinicians and geneticists in China for the past three decades. It is estimated that FAP has an incidence of between 1 in 8,000 and 1 in 10,000 individuals, and accounts for 0.94% of colorectal cancer cases in China. Recent advances in the understanding of FAP suggest that the genotype of the patient may allow for early diagnosis and surveillance, and guide surgical and chemopreventive management. However, the genetic mechanisms of FAP vary between different countries. FAP in China has its own characteristics, and this may be due to ethnic and geographical genetic variation. In the present review the clinical manifestations and genetics of FAP in China are discussed, as well as the surgical strategies, chemotherapeutics and traditional Chinese medicines used in its treatment. Increased insight into the genetic and clinical features of FAP in the Chinese population may aid in the prevention and management of the disorder.

Colorectal cancer in Chinese patients: current and emerging treatment options

Colorectal cancer is the second most common cancer in Hong Kong and its incidence is rising in economically developed Chinese cities, including Hong Kong and Shanghai. Several studies conducted in the People's Republic of China have characterized the unique molecular epidemiology of familial colorectal cancer syndromes and molecular biomarkers such as microsatellite instability and genetic mutations (eg, KRAS, NRAS, BRAF, PIK3CA, ERCC1) in Chinese populations. Interethnic differences in anticancer drug response and toxicity have been well described in many cancers, and this review examined the literature with regard to the tolerance of Chinese patients to commonly used chemotherapeutic regimens and targeted therapies for metastatic colorectal cancer. Studies on the pharmacogenomic differences in drug metabolizing and DNA repair enzymes between Chinese, North Asians, and Caucasian patients were also reviewed.

Colorectal cancer in Chinese patients: current and emerging treatment options

Colorectal cancer is the second most common cancer in Hong Kong and its incidence is rising in economically developed Chinese cities, including Hong Kong and Shanghai. Several studies conducted in the People's Republic of China have characterized the unique molecular epidemiology of familial colorectal cancer syndromes and molecular biomarkers such as microsatellite instability and genetic mutations (eg, KRAS, NRAS, BRAF, PIK3CA, ERCC1) in Chinese populations. Interethnic differences in anticancer drug response and toxicity have been well described in many cancers, and this review examined the literature with regard to the tolerance of Chinese patients to commonly used chemotherapeutic regimens and targeted therapies for metastatic colorectal cancer. Studies on the pharmacogenomic differences in drug metabolizing and DNA repair enzymes between Chinese, North Asians, and Caucasian patients were also reviewed.

Clinicopathological and genetic features of Chinese hereditary nonpolyposis colorectal cancer (HNPCC)

The aim of this study was to investigate the clinical value of different criteria and to understand the relationship between genotype and phenotype in Chinese hereditary nonpolyposis colorectal cancer (HNPCC). A total of 116 unrelated probands of suspected HNPCC families from the Fudan Colorectal Registry were studied. A total of 32, 28, and 56 families fulfilled the Amsterdam criteria, the Fudan criteria and the revised Bethesda guideline, respectively. Direct DNA sequencing of all exons of hMSH2 and hMLH1 genes were performed on all 116 samples. Mutations and clinicopathological features were compared between the groups. Thirty-two pathological germline mutations were identified. Out of 32 mutations, 16 were located at hMLH1 and 16 at hMSH2. The sensitivity of Amsterdam criteria was 50 %, specificity was 81 %, and Youden’s index was 31 %. The sensitivity of Fudan criteria was 75 %, specificity was 58 %, and Youden’s index was 33 %. Among all the 32 families with mutations, families with hMSH2 mutation had a higher ratio of synchronous and metachronous colon cancers than families with hMLH1 mutation (33 vs. 6 %, P = 0.04). Patients with hMSH2 mutation more frequently harbour synchronous and metachronous colon cancers. Fudan criteria had a little higher sensitivity and accuracy than Amsterdam criteria for identification of Chinese HNPCC.

Risk of secondary malignancy (including breast) in patients with mismatch-repair protein deficiency

Lynch syndrome (LS) is an autosomal dominant inherited disease that is associated with an increased risk for colorectal and endometrial cancer due to germline mutations in mismatch-repair (MMR) genes. Whereas primary tumors in this syndrome are widely recognized, the relative risk(s) of secondary malignancies, particularly breast cancer, in LS patients are still poorly characterized. To provide an improved assessment of these risks, MMR status was evaluated in secondary tumors from a series of patients with index tumors of known MMR status (both proficient and deficient). A total of 1252 tumors (index tumors) and all secondary malignancies were tested for MMR by immunohistochemistry (MSH2, MSH6, MLH1, PMS2) between 1992 and 2013. Tumors with MLH1/PMS2 deficiency were tested for hypermethylation or BRAF mutation, when appropriate. Of the 1252 index tumors, 162 were MMR deficient (dMMR), and, of that subset, 32 secondary tumors were identified (19.7%). In contrast, 80 secondary tumors were identified in the proficient (intact) group (7.3%). Although secondary malignancies were more common in the dMMR group (P=0.0001), there was no trend in tumor type. Specifically, breast cancer was not overly represented in the dMMR group. When secondary tumors had dMMR, they were more likely to have deficiency in MSH2/MSH6 than in MLH1/PMS2 (P=0.01). Of the patients with tumors exhibiting dMMR, women were more likely to have a dMMR secondary tumor in this series (P=0.0001); however, breast cancer was not overly represented, and our study provides no evidence that it is more frequent in LS. MSH2/MSH6 deficiency is more commonly associated with a secondary tumor compared with MLH1/PMS2 deficiency, when methylation/BRAF status is taken into account.

Risk of prostate cancer in Lynch syndrome: a systematic review and meta-analysis

It has been controversial that men carrying a DNA mismatch repair (MMR) gene mutation (Lynch syndrome) are at heightened risk of prostate cancer given that an increased risk is likely to be modest and the prevalence of prostate cancer is high. We used PubMed to search for "molecular studies" that reported MMR-deficiency status of prostate cancer tumors in men with an MMR gene mutation, and "risk studies" that reported prostate cancer risk for men known or suspected to have an MMR gene mutation relative to that for noncarriers or the general population. Of the six molecular studies, 32 of 44 [73%, 95% confidence intervals (CI), 57%-85%] prostate cancer tumors in carriers were MMR deficient, which equates to carriers having a 3.67-fold increased risk of prostate cancer (95% CI, 2.32-6.67). Of the 12 risk studies, we estimated a 2.13-fold increased risk of prostate cancer (95% CI, 1.45-2.80) for male carriers in clinic-based retrospective cohorts, 2.11 (95% CI, 1.27-2.95) for male carriers with a prior diagnosis of colorectal cancer, and 2.28 (95% CI, 1.37-3.19) for all men from mutation-carrying families. The combination of evidence from molecular and risk studies in the current literature supports consideration of prostate cancer as part of Lynch syndrome.

Mismatch repair gene mutation analysis and colonoscopy surveillance in Chinese Lynch syndrome families

BACKGROUND

Lynch syndrome (or HNPCC) is a colorectal cancer syndrome caused by germline mutations in either one of the DNA mismatch repair (MMR) genes hMLH1, hMSH2, hMSH6 or hPMS2. Mutations in hMLH1 and hMSH2 are most prevalent. Here we aimed to determine the cancer risk of MMR gene mutation carriers and, in addition, the efficacy of colonoscopy surveillance in Chinese Lynch syndrome family members with and without MMR gene mutations.

METHODS

A Lynch syndrome family registry encompassing 106 families in Northern China was recently established. Detailed pedigree data for each family were collected and hMLH1 and hMSH2 gene mutation analyses were performed. Germ-line mutations were identified in probands from 42 of these families, and additional genetic analyses were performed in each member of these 42 families to identify mutation and non-mutation carriers. Among the family members included, 180 received colonoscopy and the remaining cases were followed without colonoscopy.

RESULTS

Overall 54.8 % of the Lynch syndrome family members carried MMR gene mutations, and these mutation carriers exhibited significantly higher colorectal cancer and other Lynch syndrome-associated cancer risks as compared to non-mutation carriers. The cumulative risk for all Lynch syndrome-related cancers at age 70 was 93.8 % for both hMLH1 and hMSH2 mutation carriers, and 81.7 % and 93.1 % for colorectal cancer at this age, respectively. Whereas 43 of 102 (42.2 %) mutation carriers exhibited significant colonoscopy findings, including 10 colorectal cancers, none of 78 non-mutation carriers exhibited significant findings, and no cancers were detected. In addition, in the mutation carriers, colonoscopy surveillance led to the detection of more early stage cancers than in the non-surveillance group (70.0 % versus 36.5 %, p < 0.01).

CONCLUSION

In Lynch syndrome family members, we recommend pre-symptomatic MMR gene mutation analysis in order to identify high risk individuals for colonoscopy surveillance.

Four molecular subtypes of colorectal cancer and their precursor lesions

CONTEXT

In addition to chromosomal instability and microsatellite instability (MSI), a third pathway, epigenetic instability, has been implicated in progression to colorectal carcinogenesis. CpG island methylator phenotype (CIMP) refers to a subset of colorectal cancers (CRCs) that occur through the epigenetic instability pathway and that are characterized by widespread hypermethylation of promoter CpG island loci, resulting in the inactivation of several tumor suppressor genes or tumor-related genes. Colorectal cancers can be classified into 4 molecular subtypes according to their CIMP and MSI statuses: CIMP+/MSI+, CIMP+/MSI-, CIMP-/MSI+, and CIMP-/MSI-. There are differences between Western (United States and European Union) and Eastern (Korea and China) populations in the number of CRCs that are MSI+, and in the number of MSI+ CRCs that are CIMP+.

OBJECTIVE

To review the clinicopathologic and molecular features of the 4 molecular subtypes of CRCs and their precursor lesions, and to emphasize geographic differences in CRCs between Eastern and Western populations.

DATA SOURCES

This article is based on the author's own experimental data and a literature review of relevant articles indexed in PubMed (US National Library of Medicine).

CONCLUSION

The 4 molecular subtypes of CRC that are defined by their CIMP and MSI statuses are characterized by their own distinct clinicopathologic and molecular features and precursor lesions. In particular, the clinicopathologic features of MSI+ CRCs differ depending on the CIMP status. Further understanding of the heterogeneity in CRC molecular pathways may help to explain the diverse morphologic features of CRCs.

Frequency of extracolonic tumors in Brazilian families with Lynch syndrome: analysis of a hereditary colorectal cancer institutional registry

Lynch syndrome (LS) is caused by inherited germline mutations in mismatch repair (MMR) genes. It is one of the commonest forms of inherited predisposition to colorectal cancer (CRC), accounting for 2-5% of all CRC. LS is characterized by early age of onset, with a tendency for multiplicity and an increased risk for extra-colonic tumors at particular sites. In this study we have evaluated the frequency of extra-colonic tumors in 60 unrelated LS families fulfilling the Amsterdam criteria (ACI. ACII) from the Oncotree database of the Hereditary Colorectal Cancer Registry of the AC Camargo Hospital. All families' pedigree was extensively analyzed, varying from 2 to 6 generations with a total of 2,095 individuals evaluated. As expected, colorectal cancer was the most frequent tumor in the families (334 cases). We found 200 extracolonic tumors among all individuals with a higher ratio in women (123 cases) than men (77 cases). By far, breast cancer (32 cases) was the most frequent extracolonic manifestation in women followed by endometrial (20 cases) and uterine cervix cancer (20 cases). For man, prostate (16 cases) and stomach (12 cases) cancer were the most frequent extracolonic tumors. It is well know that establishing the diagnosis is challenging and requires knowledge and surveillance. Thus, recognition of individuals and families with hereditary predisposition to cancer according to clinical and molecular features, combined with intensive surveillance and management programs, can contribute substantially to improve results related to the diagnosis and characterization of LS.

Clinicopathological features in endometrial carcinoma associated with Lynch syndrome in China

OBJECTIVE

To study the clinicopathological characteristics of Lynch syndrome-associated endometrial carcinoma in China.

METHODS

Twenty-seven patients who fulfilled Amsterdam criteria II were classified as having Lynch syndrome-associated endometrial carcinoma (group A), and 331 patients without a family history of cancer were classified as having sporadic endometrial carcinoma (group B).

RESULTS

There were 81 malignancies in 27 families with Lynch syndrome-associated endometrial carcinoma, including colorectal cancer (24.7%), endometrial carcinoma (21.0%), and liver (12.3%), stomach (9.9%), lung (6.2%), and breast (6.2%) cancers. Mean age at the time of diagnosis was 49.7 years in group A and 56.3 years in group B (P = 0.004). Second primary cancers occurred in 33.3% of patients in group A and 5.1% in group B (P = 0.000). The most common second primary cancers were colorectal cancer (44%) and ovarian cancer (22%). The percentage of obese patients was higher in group A (P= 0.013). There was no difference between the 2 groups in incidence of diabetes mellitus or hypertension or in histological type and International Federation of Gynecology and Obstetrics stage. The 5-year survival rates for groups A and B were 96.2% and 79.6%, respectively. Prognosis for group A was better than for group B (P = 0.045).

CONCLUSIONS

Some clinicopathological features of Lynch syndrome-associated endometrial carcinoma, such as early onset and multiple primary carcinomas are similar in the Chinese and American/European populations. However, the Chinese population had a unique family cancer distribution that included lung and breast cancers. Well-differentiated grade and good prognosis imply better biobehavior of Lynch syndrome-associated endometrial carcinoma in the Chinese population.

Hereditary colorectal cancer syndromes and the role of the surgical oncologist

The expanding understanding of the genetic basis to hereditary colon cancer syndromes is dismantling previously conceived categorizations and shedding light on why those schemes often failed in past. This review highlights evolving concepts regarding the genetic diagnosis and clinical management of the more commonly inherited colorectal cancer syndromes, including a discussion of recently described familial syndromes. This review also addresses clinician responsibilities in recognition of familial syndromes and provision of counseling.

Clinical features and mismatch repair genes analyses of Chinese suspected hereditary non-polyposis colorectal cancer: a cost-effective screening strategy proposal

China has the largest numbers of hereditary non-polyposis colorectal cancer (HNPCC) patients based on its population of 1.4 billion. However, the clinical data and mismatch repair (MMR) gene analyses have been limited. Here we performed microsatellite instability (MSI) and immunohistochemistry (IHC) analyses on a series of patients with a high-risk for HNPCC: 61 patients with family histories fulfilling Amsterdam criteria II (ACII-HNPCC) or suspected HNPCC criteria (S-HNPCC), and 106 early onset colorectal cancer (CRC) patients. Sixty late-onset CRC patients were used as control. Methylation of the hMLH1 promoter was analyzed on tumors lacking hMLH1 expression. MMR germ-line mutations were screened on patients with tumors classified as MSI-H/L or negative for IHC. We identified 27 germ-line MMR variants in the 167 patients with a high-risk for HNPCC while only one germ-line mutation in hMSH6 was found in the late-onset CRC group. Of those, 23 were pathogenic mutations. The high incidence of gastric and hepatobiliary cancers coupled with the increasing number of small families in China reduces the sensitivity (43.5%, 30.4%) and positive predictive value (PPV) (45.5%, 17.9%) of the ACII- or S-HNPCC criteria. MSI or IHC testing are highly sensitive in detecting pathogenic mutations (sensitivities = 91.3% and 95.6%, respectively), but the PPVs are quite low (25.6% and 27.8%, respectively). Considering that all 12 tumors with pathogenic mutations in hMLH1 also showed promoter unmethylation, the sensitivity of IHC in conjunction with hMLH1 promoter methylation analysis is not reduced, but the PPV was increased from 27.8% to 61.1%, and the total cost was greatly reduced.

Polymorphism in the promoter region of the NFKB1 gene increases the risk of sporadic colorectal cancer in Swedish but not in Chinese populations

OBJECTIVE

An insertion/deletion polymorphism (-94ins/delATTG) in the promoter region of the NFKB1 gene correlates to an increased risk of ulcerative colitis, a known risk factor for colorectal cancer, but this polymorphism has not been studied in colorectal cancer patients. The purpose of this study was to investigate whether this polymorphism is related to colorectal cancer risk and clinicopathological variables.

MATERIAL AND METHODS

Case samples were taken from four groups of Swedish patients: 193 unselected patients, 90 patients with > or =3 affected 1st-degree relatives, 85 patients with 2 affected 1st-degree relatives, and 109 sporadic cancer patients, and one group of 193 unselected Chinese patients. Controls included 439 Swedish and 458 Chinese healthy individuals. Genotypes were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism.

RESULTS

The deletion increased the risk of colorectal cancer among Swedish unselected patients (OR =3.81, 95% CI: 2.17-6.69, p <0.0001 for heterozygote deletion, and OR=4.65, 95% CI: 2.43-8.89, p <0.0001 for homozygote deletion) and sporadic cancer patients (OR =7.73, 95% CI: 3.06-19.57, p <0.0001 for heterozygote deletion, and OR =6.58, 95% CI: 2.35-18.43, p <0.0001 for homozygote deletion) compared to homozygote insertion (wild-type), but not among the other Swedish or Chinese patients (p >0.05). Similar evidence was seen in age-adjusted analyses (p <0.0001). The polymorphism did not correlate to clinicopathological variables (p >0.05).

CONCLUSIONS

Deletion of the polymorphism was associated with increased susceptibility to sporadic colorectal cancers in the Swedish population, but not in the Swedish patients with a family history of colorectal cancer or in Chinese patients.

Hereditary nonpolyposis colorectal cancer (Lynch Syndrome) in Argentina: report from a referral hospital register

PURPOSE

The first Argentine experience with epidemiologic, molecular, and genetic counseling data is reported.

METHODS

We analyzed 43 families fulfilling Amsterdam criteria identified from a prospective database with data from 779 relatives.

RESULTS

Eleven families (25.6 percent) presented as Lynch I, 29 (67.4 percent) as Lynch II, and 3 (7 percent) as Muir-Torre syndrome. Among the 306 affected members, 197 cases of colorectal cancer were identified (mean age at diagnosis, 52.1 (range, 21-90) years). The most frequent extracolonic tumors were gastric adenocarcinoma in males and endometrium adenocarcinoma in females. A high incidence of breast cancer was observed (16 cases among 155 females, crude rate: 11,594.20/100,000). Twenty-seven patients (8.8 percent) developed more than one tumor. These patients were younger than those with only one tumor (45 vs. 51 years; P = 0.001). In 5 of 11 patients who underwent molecular sequencing, a pathologic mutation was found. A novel C deletion at 1910 nucleotide, codon 637, exon 12 of MSH2 gene was identified in a family with a strong aggregation of breast cancer with lack of MSH2 immunohistochemical staining. For 78.2 percent of counseled individuals, this session represented the first time they received information, and 73.9 percent stated that their physicians were unaware of their family background.

CONCLUSIONS

Argentine families presented a high incidence of stomach cancer. The elevated incidence of breast cancer and its association with a novel hMSH2 mutation bring to consideration the inclusion of this malignancy as part of the syndrome. A lack of awareness by both physicians and persons at risk was observed.

Is gastric cancer part of the tumour spectrum of hereditary non-polyposis colorectal cancer? A molecular genetic study

BACKGROUND

Gastric cancer is the second most common extracolonic malignancy in individuals with hereditary non-polyposis colorectal cancer (HNPCC)/Lynch syndrome. As gastric cancer is relatively common in the general population as well, it is not clear whether or not gastric cancer is a true HNPCC spectrum malignancy.

AIM

To determine whether or not gastric cancer is a true HNPCC spectrum malignancy.

SUBJECTS AND METHODS

The molecular and clinicopathological profiles of gastric cancers (n = 13) from HNPCC mutation carriers were evaluated and compared with the profiles of sporadic gastric cancers (n = 46) stratified by histology and microsatellite instability (MSI) status.

RESULTS

This study on sporadic and HNPCC gastric cancers revealed several important universal associations. Loss of heterozygosity in the adenomatous polyposis coli (APC) region was associated with intestinal histology regardless of the MSI (p = 0.007). KRAS-mutations (p = 0.019) and frameshift mutations in repeat tracts of growth-regulatory genes (p<0.001) were associated with MSI tumours being absent in microsatellite stable (MSS) tumours. The average number of methylated tumour suppressor gene loci among the 24 genes studied (methylation index) was higher in MSI than in MSS tumours regardless of histology (p<0.001). Gastric cancers from HNPCC mutation carriers resembled sporadic intestinal MSI gastric cancers, except that MLH1 promoter methylation was absent (p<0.001) and the general methylation index was lower (p = 0.038), suggesting similar, but not identical, developmental pathways. All these lacked the mismatch repair protein corresponding to the germline mutation and displayed high MSI.

CONCLUSION

The present molecular evidence, combined with the previous demonstration of an increased incidence relative to the general population, justify considering gastric cancers as true HNPCC spectrum malignancies.

MYH mutations are rare in prostate cancer

PURPOSE

Oxidative stress is considered a risk factor for prostate cancer development and is associated with the production of reactive oxygen species (ROS). The base excision repair gene MYH protects against ROS-mediated damage to DNA. Inherited MYH mutations predispose to colorectal adenomas and cancer. A compromised base-excision repair function due to defective MYH may contribute to prostate carcinogenesis. Here, we examine the genetic contribution of MYH to prostate cancer risk.

METHODS

Patients diagnosed with high-grade prostatic intraepithelial neoplasia (HGPIN) alone (n = 45), prostate cancer alone (n = 123) or both (n = 82) were screened for the two most common mutations in the MYH gene using PCR-based RFLP analysis. A single patient with an inherited MYH mutation as well as a subset of 26 patients presenting with a family history of colorectal cancer were screened for additional MYH mutations by direct sequencing of the entire coding region.

RESULTS

Biallelic germline mutations in MYH were not detected among prostate cancer patients. Only a single patient was a heterozygous carrier for the Y165C missense mutation. Allelic deletion or somatic mutation of the remaining MYH allele was not identified in this patient's tumor DNA. Two patients harbored V22M polymorphism and three patients were carriers of Q324H polymorphism.

CONCLUSIONS

MYH mutations are unlikely to contribute to prostate cancer risk.

The phenotypic expression of three MSH2 mutations in large Newfoundland families with Lynch syndrome

To compare the phenotypic expression of three different MSH2 mutations causing Lynch syndrome, 290 family members at 50% risk of inheriting a mutation were studied. Two truncating mutations of the MSH2 gene have been identified in Newfoundland: an exon 8 deletion in five families (N=74 carriers) and an exon 4-16 deletion in one family (N=65 carriers). The third mutation was an intron 5 splice site mutation resulting in deletion of exon 5 in RNA and occurred in 12 families (N=151 carriers). Age to onset of first cancer, first colorectal cancer (CRC), first extracolonic cancers and death were compared. By age 60, 89% of family members with the intron 5 mutation, 81% with the exon 8 deletion, and 85% with the exon 4-16 deletion had developed cancer. For all three mutations males had a higher age-related risk of CRC and death compared to females. In the intron 5 splice site mutation carriers, the number of transitional cell cancers of the urinary tract was significantly lower and time to first ovarian cancer was significantly higher than in the carriers of the genomic deletions. The incidence of CRC in MSH2 mutation carriers, exposed to the same environment, is not modified by the specific mutation, although there is a suggestion that type of mutation may influence development of some extracolonic cancers.

Molecular models for the tissue specificity of DNA mismatch repair-deficient carcinogenesis

A common feature of all the known cancer genetic syndromes is that they predispose only to selective types of malignancy. However, many of the genes mutated in these syndromes are ubiquitously expressed, and influence seemingly universal processes such as DNA repair or cell cycle control. The tissue specificity of cancers that arise from malfunction of these apparently universal traits remains a key puzzle in cancer genetics. Mutations in DNA mismatch repair (MMR) genes cause the most common known cancer genetic syndrome, hereditary non-polyposis colorectal cancer, and the fundamental biology of MMR is one of the most intensively studied processes in laboratories all around the world. This review uses MMR as a model system to understand mechanisms that may explain the selective development of tumors in particular cell types despite the universal nature of this process. We evaluate recent data giving insights into the specific tumor types that are attributable to defective MMR in humans and mice under different modes of inheritance, and propose models that may explain the spectrum of cancer types observed.

[Prophylactic surgery for hereditary non-polyposis colorectal cancer]

The most frequent hereditary colorectal cancer predisposition is Lynch syndrome, or hereditary non-polyposis colorectal cancer. The option of prophylactic surgery relies on the penetrance of the genetic defect and the heterogeneity of the condition. Since 20% of all mutation carriers never move on to develop cancer, the purely prophylactic setting is not indicated. However, when colorectal cancer is diagnosed, the question arises if the patient may benefit from extended surgery -- total colectomy or (restorative) proctocolectomy. These patients should be entered into the ongoing prospective-randomized study by German Cancer Aid (http://www.hnpcc-studie.de). Due to substantially increased cancer risk and poor surveillance options, the endometrium and stomach are also subject to the question of prophylactic intervention.

Hereditary colorectal cancer in china

The purpose of this article is to review basic research as well as clinical studies on Chinese hereditary colorectal cancer. Hereditary nonpolyposis colorectal cancer (HNPCC, Lynch syndrome) accounts for 2.2% of all colorectal cancer, and Chinese criteria for suspected HNPCC have been developed. Germline mutations as well as large genomic rearrangements of mismatch repair (MMR) genes are responsible for this syndrome. Gastric cancer is the second most common cancer in Chinese HNPCC patients. Contrary to sporadic colorectal cancer in the Chinese population, HNPCC does not typically present with rectal cancer. Incidence of familial adenomatous polyposis (FAP) in China is approximately 1.5/100,000. Polyps in Chinese FAP patients can emerge as early as 16 months old, but malignant transformation usually occurs in the third and fourth decade. Total resection of the colon and rectum is necessary in FAP patients. For unresectable duodenal polyps, chemopreventive agents may be used.