Hereditary non-polyposis colorectal cancer: clinical features and survival. Results from the Danish HNPCC register

National Experiences from 30 Years of Provider-Mediated Cascade Testing in Lynch Syndrome Families-The Danish Model

Cascade genetic testing and surveillance reduce morbidity and mortality in Lynch syndrome. However, barriers to conveying information about genetic disorders within families result in low uptake of genetic testing. Provider-mediated interventions may increase uptake but raise legal and ethical concerns. We describe 30 years of national experience with cascade genetic testing combining family- and provider-mediated contact in Lynch syndrome families in the Danish Hereditary Non-Polyposis Colorectal Cancer (HNPCC) Register. We aimed to estimate the added value of information letters to family members in Lynch syndrome families (provider-mediated contact) compared to family members not receiving such letters and thus relying on family-mediated contact. National clinical practice for cascade genetic testing, encompassing infrastructure, legislation, acceptance, and management of the information letters, is also discussed. Cascade genetic testing resulted in 7.3 additional tests per family. Uptake of genetic testing was 54.4% after family-mediated and 64.9% after provider-mediated contact, corresponding to an odds ratio of 1.8 (p < 0.001). The uptake of genetic testing was highest in the first year after diagnosis of Lynch syndrome in the family, with 72.5% tested after provider-mediated contact. In conclusion, the Danish model combining family- and provider-mediated contact can increase the effect of cascade genetic testing.

Polyposis and Oncologic Outcomes in Young-onset Sporadic Colorectal Cancer

Aim

The present study aimed to investigate the effect of the presence of polyposis in sporadic early-onset colorectal cancer (EOCRC) on clinicopathological and oncological outcomes.

Methods

The retrospective study included patients with sporadic colorectal cancer aged 16 to 50 years who underwent curative resection at the general surgery clinics in two healthcare centers between 2013 and 2019. Patients were divided into two groups: polyposis and nonpolyposis. Clinicopathological characteristics and oncological outcomes were compared between the two groups.

Results

A total of 127 patients were included, of whom 60.6% were men. There were 25 (19.68%) patients in the polyposis group and 102 (80.31%) patients in the nonpolyposis group. Seventy-one (69.6%) of the nonpolyposis group and 23 (92.0%) of the polyposis group had adenocarcinoma histological types. The total number of patients with mucinous tumor and signet ring cell carcinoma in the nonpolyposis and polyposis groups was 31 (30.4%) and 2 (8.0%), respectively (p = 0.042). Five-year overall survival (OS) was 60 and 72% in the nonpolyposis and polyposis groups, respectively, and no significant difference was found (p = 0.332). In univariate analysis, American Joint Committee on Cancer (AJCC) tumor stage (pT) ≥3–4, lymph node positivity, presence of mucinous tumor and signet ring cell carcinoma, lymphovascular invasion, and advanced tumor-lymph nodesmetastasis (TNM) stage (III–IV) were found to be significant negative prognostic factors for OS, whereas none of these parameters were found to be prognostic factors in multivariate analysis. The presence of polyposis was not a significant factor on both univariate and multivariate analyses.

Conclusion

Although the sporadic EOCRC cases developing on the basis of polyposis can have slightly better oncological outcomes, these outcomes are mostly similar to those of cases with nonpolyposis.

How to cite this article

Aday U, Kafadar MT, Oğuz A, et al. Polyposis and Oncologic Outcomes in Young-onset Sporadic Colorectal Cancer. Euroasian J Hepato-Gastroenterol 2021;11(1):6–10.

Prognostic Relevance of MLH1 and MSH2 Mutations in Hereditary Non-Polyposis Colorectal Cancer Patients

Aims and Background

Colorectal carcinoma patients from hereditary non-polyposis colorectal cancer families are suggested to have a better prognosis than sporadic colorectal carcinoma cases. Since the majority of hereditary non-polyposis colorectal cancer-related colorectal carcinomas are characterized by microsatellite instability due to germline mutations in DNA mismatch repair genes, this is consistent with the prolonged survival observed in sporadic microsatellite instability-positive colorectal carcinoma compared to microsatellite stable cases. However, a fraction of colorectal carcinoma cases belongs to families that, despite fulfilling the clinical criteria for hereditary non-polyposis colorectal cancer, do not carry mismatch repair gene mutations. Our aim was to verify to what extent the genotypic heterogeneity influences the prognosis of hereditary non-polyposis colorectal cancer patients.

Methods

A survival analysis was performed on 526 colorectal carcinoma cases from 204 Amsterdam Criteria-positive hereditary non-polyposis colorectal cancer families. Enrolled cases were classified as MLH1-positive, MSH2-positive and mutation-negative, according to the results of genetic testing in each family.

Results

Five-year survival rates were 0.73 (95% CI, 0.66-0.80), 0.75 (95% CI, 0.66-0.84) and 0.62 (95% CI, 0.55-0.68) for MLH1-positive, MSH2-positive and mutation-negative groups, respectively (logrank test, P = 0.01). Hazard ratio, computed using Cox regression analysis and adjusted for age, sex, tumor site and stage, was 0.71 (95% CI, 0.51-0.98) for the mutation-positive compared to the mutation-negative group. Moreover, in the latter group, patients with microsatellite instability-positive colorectal carcinomas showed a better outcome than microsatellite stable cases (5-year survival rates, 0.81 and 0.60, respectively; logrank test, P = 0.006).

Conclusions

Our results suggest that the prognosis of hereditary non-polyposis colorectal cancer-related colorectal carcinoma patients depends on the associated constitutional mismatch repair genotype.

Familial and sporadic pancreatic cancer share the same molecular pathogenesis

Pancreatic ductal adenocarcinoma (PDAC) is nearly uniformly lethal, with a median overall survival in 2014 of only 6 months. The genetic progression of sporadic PDAC (SPC) is well established, with common somatic alterations in KRAS, p16/CDKN2A, TP53, and SMAD4/DPC4. Up to 10 % of all PDAC cases occur in families with two or more affected first-degree relatives (familial pancreatic cancer, FPC), but these cases do not appear to present at an obviously earlier age of onset. This is unusual because most familial cancer syndrome patients present at a substantially younger age than that of corresponding sporadic cases. Here we collated the reported age of onset for FPC and SPC from the literature. We then used an integrated approach including whole exomic sequencing, whole genome sequencing, RNA sequencing, and high density SNP microarrays to study a cohort of FPC cell lines and corresponding germline samples. We show that the four major SPC driver genes are also consistently altered in FPC and that each of the four detection strategies was able to detect the mutations in these genes, with one exception. We conclude that FPC undergoes a similar somatic molecular pathogenesis as SPC, and that the same gene targets can be used for early detection and minimal residual disease testing in FPC patients.

Colonoscopy findings in high-risk individuals compared to an average-risk control population

BACKGROUND AND AIMS

There is clear evidence of reduced morbidity and mortality from regular colonoscopy programs in patients with Lynch syndrome (LS). Today, also individuals with empirically increased risks of colorectal cancer (CRC) are offered colonoscopic surveillance. The aim was to compare the findings at the first screening colonoscopy in LS carriers, and individuals with an increased risk of bowel cancer due to family history of CRC with a control population.

METHODS

Altogether 1397 individuals with an increased risk for CRC were divided in four risk groups: one with LS carriers and three groups with individuals with different family history of CRC. The findings were compared between the different risk groups and a control group consisting of 745 individuals from a control population who took part in a population-based colonoscopy study.

RESULTS

In LS, 30% of the individuals had adenomas and 10% advanced adenomas. The corresponding figures in the other risk groups were 14-24% and 4-7%, compared with 10% and 3% in the control group. The relative risk of having adenomas and advanced adenomas was, compared to controls, significantly higher for all risk groups except the group with the lowest risk. Age was a strong predictor for adenomas and advanced adenomas in both risk individuals and controls.

CONCLUSIONS

Individuals with a family history of CRC have a high prevalence and cumulative risk of adenomas and advanced adenomas, and screening is motivated also in this risk group.

A systematic review and economic evaluation of diagnostic strategies for Lynch syndrome

BACKGROUND

Lynch syndrome (LS) is an inherited autosomal dominant disorder characterised by an increased risk of colorectal cancer (CRC) and other cancers, and caused by mutations in the deoxyribonucleic acid (DNA) mismatch repair genes.

OBJECTIVE

To evaluate the accuracy and cost-effectiveness of strategies to identify LS in newly diagnosed early-onset CRC patients (aged < 50 years). Cascade testing of relatives is employed in all strategies for individuals in whom LS is identified.

DATA SOURCES AND METHODS

Systematic reviews were conducted of the test accuracy of microsatellite instability (MSI) testing or immunohistochemistry (IHC) in individuals with CRC at risk of LS, and of economic evidence relating to diagnostic strategies for LS. Reviews were carried out in April 2012 (test accuracy); and in February 2012, repeated in February 2013 (economic evaluations). Databases searched included MEDLINE (1946 to April week 3, 2012), EMBASE (1980 to week 17, 2012) and Web of Science (inception to 30 April 2012), and risk of bias for test accuracy was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) quality appraisal tool. A de novo economic model of diagnostic strategies for LS was developed.

RESULTS

Inconsistencies in study designs precluded pooling of diagnostic test accuracy results from a previous systematic review and nine subsequent primary studies. These were of mixed quality, with significant methodological concerns identified for most. IHC and MSI can both play a part in diagnosing LS but neither is gold standard. No UK studies evaluated the cost-effectiveness of diagnosing and managing LS, although studies from other countries generally found some strategies to be cost-effective compared with no testing. The de novo model demonstrated that all strategies were cost-effective compared with no testing at a threshold of £20,000 per quality-adjusted life-year (QALY), with the most cost-effective strategy utilising MSI and BRAF testing [incremental cost-effectiveness ratio (ICER) = £5491 per QALY]. The maximum health benefit to the population of interest would be obtained using universal germline testing, but this would not be a cost-effective use of NHS resources compared with the next best strategy. When the age limit was raised from 50 to 60 and 70 years, the ICERs compared with no testing increased but remained below £20,000 per QALY (except for universal germline testing with an age limit of 70 years). The total net health benefit increased with the age limit as more individuals with LS were identified. Uncertainty was evaluated through univariate sensitivity analyses, which suggested that the parameters substantially affecting cost-effectiveness: were the risk of CRC for individuals with LS; the average number of relatives identified per index patient; the effectiveness of colonoscopy in preventing metachronous CRC; the cost of colonoscopy; the duration of the psychological impact of genetic testing on health-related quality of life (HRQoL); and the impact of prophylactic hysterectomy and bilateral salpingo-oophorectomy on HRQoL (this had the potential to make all testing strategies more expensive and less effective than no testing).

LIMITATIONS

The absence of high-quality data for the impact of prophylactic gynaecological surgery and the psychological impact of genetic testing on HRQoL is an acknowledged limitation.

CONCLUSIONS

Results suggest that reflex testing for LS in newly diagnosed CRC patients aged < 50 years is cost-effective. Such testing may also be cost-effective in newly diagnosed CRC patients aged < 60 or < 70 years. Results are subject to uncertainty due to a number of parameters, for some of which good estimates were not identified. We recommend future research to estimate the cost-effectiveness of testing for LS in individuals with newly diagnosed endometrial or ovarian cancer, and the inclusion of aspirin chemoprevention. Further research is required to accurately estimate the impact of interventions on HRQoL.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42012002436.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

The evolution of colorectal cancer genetics-Part 2: clinical implications and applications

The genetic understanding of colorectal cancer (CRC) continues to grow, and it is now estimated that 10% of the population has a known hereditary CRC syndrome. This article will examine the evolving surgical and medical management of hereditary CRC syndromes, and the impact of tumor genetics on therapy. This review will focus on the most common hereditary CRC-prone diseases seen in clinical practice, which include Lynch syndrome (LS), familial adenomatous polyposis (FAP) & attenuated FAP (AFAP), MutYH-associated polyposis (MAP), and serrated polyposis syndrome (SPS). Each section will review the current recommendations in the evaluation and treatment of these syndromes, as well as review surgical management and operative planning. A highly detailed multigeneration cancer family history with verified genealogy and pathology documentation whenever possible, coupled with germline mutation testing when indicated, is critically important to management decisions. Although caring for patients with these syndromes remains complex, the application of this knowledge facilitates better treatment of both individuals and their affected family members for generations to come.

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.

Hereditary ovarian and breast cancer: what have we learned?

An autosomal-dominant inherited trait predisposing women to both breast cancer (BC) and ovarian cancer (OC) was first described in 1971. Subsequent strides were made in identifying mutations in the eventually cloned genes BRCA1 and BRCA2 as being responsible for hereditary BC and OC (HBOC) in many women with early-onset HBOC. More recently, modifiers of BC risk have also been identified and are under study. The biological and molecular genetic pathways for malignant transformation in OC (ovarian epithelium and/or epithelium of the fallopian tube or, possibly, the endometrium and endocervix) remain elusive. The answer to the question 'What have we learned?' which is part of our chapter title unfortunately remains incomplete. However, intensive worldwide research indicates that its malignant transformation is the product of a multi-step process where there is an array of mutations which account for three or more classes of genes, inclusive of proto-oncogenes, tumor suppressor genes and mutator genes. This causal uncertainty heralds an enormous clinical-pathology dilemma, given the fact that epithelial OC, together with related Müllerian duct carcinoma, harbor the highest fatality rates of all gynecologic malignancies.

Survival of patients with Stage III colon cancer is improved in hereditary non-polyposis colorectal cancer compared with sporadic cases. A Danish registry based study

AIM

Patients with hereditary non-polyposis colorectal cancer (HNPCC) seem to have a better prognosis than those with sporadic colorectal cancer (CRC). The aim was to compare survival after Stage III CC in patients with HNPCC with those having sporadic CC.

METHOD

A total of 230 patients with hereditary cancer from the Danish HNPCC Register and 3557 patients with sporadic CC from the Danish Colorectal Cancer Database, diagnosed during May 2001-December 2008, were included. HNPCC patients were classified according to mismatch repair mutation status and family pedigree. Sporadic cases had no known family history of cancer. Patient characteristics, geographical differences and survival data were analysed.

RESULTS

The overall survival (OS) was better in HNPCC patients compared with sporadic CC after stratification for sex and age (P = 0.02; CI 1.04-1.7). The 5-year survival was 70% in HNPCC patients compared with 56% in sporadic CC (P < 0.001). No survival difference was found between HNPCC subgroups but a tendency to better OS was seen in patients with Lynch syndrome. No geographical differences in OS were found. The median follow-up was 3.9 (0-9.5) years for HNPCC vs 3.2 (0-9.6) years for sporadic CC.

CONCLUSION

HNPCC patients with Stage III CC have a better OS compared with sporadic CC. No significant difference in OS was found within HNPCC subgroups.

Relevance, pathogenesis, and testing algorithm for mismatch repair-defective colorectal carcinomas: a report of the association for molecular pathology

Loss-of-function defects in DNA mismatch repair (MMR), which manifest as high levels of microsatellite instability (MSI), occur in approximately 15% of all colorectal carcinomas (CRCs). This molecular subset of CRC characterizes patients with better stage-specific prognoses who experience no benefit from 5-fluorouracil chemotherapy. Most MMR-deficient (dMMR) CRCs are sporadic, but 15% to 20% are due to inherited predisposition (Lynch syndrome). High penetrance of CRCs in germline MMR gene mutation carriers emphasizes the importance of accurate diagnosis of Lynch syndrome carriers. Family-based (Amsterdam), patient/family-based (Bethesda), morphology-based, microsatellite-based, and IHC-based screening criteria do not individually detect all germline mutation carriers. These limitations support the use of multiple concurrent tests and the screening of all patients with newly diagnosed CRC. This approach is resource intensive but would increase detection of inherited and de novo germline mutations to guide family screening. Although CRC prognosis and prediction of 5-fluorouracil response are similar in both the Lynch and sporadic dMMR subgroups, these subgroups differ significantly with regard to the implications for family members. We recommend that new CRCs should be classified into sporadic MMR-proficient, sporadic dMMR, or Lynch dMMR subgroups. The concurrent use of MSI testing, MMR protein IHC, and BRAF c.1799T>A mutation analysis would detect almost all dMMR CRCs, would classify 94% of all new CRCs into these MMR subgroups, and would guide secondary molecular testing of the remainder.

A hidden Markov model-based algorithm for identifying tumour subtype using array CGH data

Background

The recent advancement in array CGH (aCGH) research has significantly improved tumor identification using DNA copy number data. A number of unsupervised learning methods have been proposed for clustering aCGH samples. Two of the major challenges for developing aCGH sample clustering are the high spatial correlation between aCGH markers and the low computing efficiency. A mixture hidden Markov model based algorithm was developed to address these two challenges.

Results

The hidden Markov model (HMM) was used to model the spatial correlation between aCGH markers. A fast clustering algorithm was implemented and real data analysis on glioma aCGH data has shown that it converges to the optimal cluster rapidly and the computation time is proportional to the sample size. Simulation results showed that this HMM based clustering (HMMC) method has a substantially lower error rate than NMF clustering. The HMMC results for glioma data were significantly associated with clinical outcomes.

Conclusions

We have developed a fast clustering algorithm to identify tumor subtypes based on DNA copy number aberrations. The performance of the proposed HMMC method has been evaluated using both simulated and real aCGH data. The software for HMMC in both R and C++ is available in ND INBRE website http://ndinbre.org/programs/bioinformatics.php.

Management of young onset colorectal cancer: divergent practice in the East of England

AIM

According to the revised Bethesda Guidelines, colorectal cancer (CRC) occurring under age 50 years should be screened to exclude Lynch syndrome. However, in current practice in East Anglia, tumour screening is initiated only after genetics referral, reserved for those with a strong pedigree. This study aimed to determine how many patients with young-onset CRC undergo tumour screening in hospitals in East Anglia.

METHOD

A retrospective case notes review over 5 years in four hospitals was undertaken to determine what proportion of those with young-onset CRC underwent referral for tumour screening and to assess local practices in terms of patient counselling and management.

RESULTS

One hundred and twenty-two patients were included. There was an average yearly caseload of 6-9 patients per hospital. Documented family history was rare, as was counselling concerning metachronous and extra-colonic tumour risk and CRC risk in relatives. The rate of referral for genetic testing varied from 44% to 65%. Postoperative colonoscopic surveillance was inconsistent.

CONCLUSION

Many patients with young-onset CRC are managed as sporadic cancers, without Lynch syndrome having been excluded. This may have implications for survival of patients and any affected relatives. A streamlined management algorithm for tumour screening and genetics referral is recommended.

Survival of MUTYH-associated polyposis patients with colorectal cancer and matched control colorectal cancer patients

BACKGROUND

MUTYH-associated polyposis is a recessively inherited disorder characterized by a lifetime risk of colorectal cancer that is up to 100%. Because specific histological and molecular genetic features of MUTYH-associated polyposis colorectal cancers might influence tumor behavior and patient survival, we compared survival between patients with MUTYH-associated polyposis colorectal cancer and matched control patients with colorectal cancer from the general population.

METHODS

In this retrospective multicenter cohort study from Europe, 147 patients with MUTYH-associated polyposis colorectal cancer were compared with 272 population-based control patients with colorectal cancer who were matched for country, age at diagnosis, year of diagnosis, stage, and subsite of colorectal cancer. Kaplan-Meier survival and Cox regression analyses were used to compare survival between patients with MUTYH-associated polyposis colorectal cancer and control patients with colorectal cancer. All statistical tests were two-sided.

RESULTS

Five-year survival for patients with MUTYH-associated polyposis colorectal cancer was 78% (95% confidence interval [CI] = 70% to 84%) and for control patients was 63% (95% CI = 56% to 69%) (log-rank test, P = .002). After adjustment for differences in age, stage, sex, subsite, country, and year of diagnosis, survival remained better for MUTYH-associated polyposis colorectal cancer patients than for control patients (hazard ratio of death = 0.48, 95% CI = 0.32 to 0.72).

CONCLUSIONS

In a European study cohort, we found statistically significantly better survival for patients with MUTYH-associated polyposis colorectal cancer than for matched control patients with colorectal cancer.

Germline genetic variation, cancer outcome, and pharmacogenetics

Studies of the role of germline or inherited genetic variation on cancer outcome can fall into three distinct categories. First, the impact of highly penetrant but lowly prevalent mutations of germline DNA on cancer prognosis has been studied extensively for BRCA1 and BRCA2 mutations as well as mutations related to hereditary nonpolyposis colorectal cancer syndrome. These mainly modest-sized analyses have produced conflicting results. Although some associations have been observed, they may not be independent of other known clinical or molecular prognostic factors. Second, the impact of germline polymorphisms on cancer prognosis is a burgeoning field of research. However, a deeper understanding of potentially confounding somatic changes and larger multi-institutional, multistage studies may be needed before consistent results are seen. Third, research examining the impact of germline genetic variation on differential treatment response or toxicity (pharmacogenetics) has produced some proof-of-principle results. Putative germline pharmacogenetic predictors of outcome include DPYD polymorphisms and fluorouracil toxicity, UGT1A1 variation and irinotecan toxicity, and CYP2D6 polymorphisms and tamoxifen efficacy, with emerging data on predictors of molecularly targeted or biologic drugs. Here we review data pertaining to these germline outcome and germline toxicity relationships.

Decision Model of Segmental Compared With Total Abdominal Colectomy for Colon Cancer in Hereditary Nonpolyposis Colorectal Cancer

Purpose

In choosing the appropriate surgical option for patients with colon cancer and Lynch syndrome, goals of treatment are to maximize life expectancy while preserving quality of life. This study constructs a decision model that encompasses these two related considerations.

Methods

We constructed a state-transition (Markov) model based on assumptions obtained from available data sources and published literature. Two strategies were considered for the treatment of colon cancer in a patient with Lynch syndrome: segmental colectomy (SEG) and total abdominal colectomy (TAC) with ileorectal anastomosis. Quality-adjusted life years (QALYs) were calculated based on utility states for patients based on the colectomy they received. Multiple sensitivity analyses were planned to examine the impact of each assumption on model results.

Results

For young (30-year-old) patients with Lynch syndrome, mean survival was slightly better with TAC than with SEG (34.8 v 35.5 years). When QALYs were considered, the two strategies were approximately equivalent, with QALYs per patient of 21.5 for SEG and 21.2 for TAC. With advancing age, SEG becomes a more favorable strategy. Results of our model were most sensitive to the utility state of TAC (relative to SEG), rates of metachronous occurrence, and stage of cancer at the time of such occurrence.

Conclusion

SEG and TAC are approximately equivalent strategies for patients with colon cancer and Lynch syndrome. The decision regarding which operation is preferable should be made on the basis of patient factors and preferences, with special emphasis on age and the ability of the patient to utilize intensive surveillance.

Hereditary non-polyposis colorectal cancer or Lynch syndrome: the gynaecological perspective

PURPOSE OF REVIEW

Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome is characterized by a number of other cancers including colorectal, endometrial and ovarian cancer. This review covers the gynaecological aspects of managing women with HNPCC: diagnostic criteria, molecular tests for diagnosis, cancer risks and different strategies for surveillance and prevention.

RECENT FINDINGS

Studies correcting for ascertainment bias found slightly lower penetrance estimates than those obtained from high-risk families. HNPCC linked ovarian cancer presents at an earlier age and stage and has similar survival rates as sporadic cancer. In endometrial tumours, microsatellite instability or immunohistochemistry has limited effectiveness in selecting individuals for genetic testing, due to molecular differences. Population-based data indicate that a significant proportion of mismatch repair gene carriers would be missed by current clinical criteria. Effective risk prediction models complement clinical risk assessment. Effectiveness of screening is unproven and prophylactic surgery is the best preventive option for women who have completed their families. Multimodal screening protocols from the age of 30-35 years are being evaluated.

SUMMARY

Risk of endometrial cancer in women with Lynch syndrome is as high as the risk of colorectal cancer. Further research is needed to identify the appropriate strategy for clinical risk assessment and optimize screening. A multidisciplinary approach is necessary to manage these women.

Hereditary ovarian carcinoma: heterogeneity, molecular genetics, pathology, and management

Hereditary ovarian cancer accounts for at least 5% of the estimated 22,000 new cases of this disease during 2009. During this same time, over 15,000 will die from malignancy ascribed to ovarian origin. The bulk of these hereditary cases fits the hereditary breast-ovarian cancer syndrome, while virtually all of the remainder will be consonant with the Lynch syndrome, disorders which are autosomal dominantly inherited. Advances in molecular genetics have led to the identification of BRCA1 and BRCA2 gene mutations which predispose to the hereditary breast-ovarian cancer syndrome, and mutations in mismatch repair genes, the most common of which are MSH2 and MLH1, which predispose to Lynch syndrome. These discoveries enable relatively certain diagnosis, limited only by their variable penetrance, so that identification of mutation carriers through a comprehensive cancer family history might be possible. This paper reviews the subject of hereditary ovarian cancer, with particular attention to its molecular genetic basis, its pathology, and its phenotypic/genotypic heterogeneity.

Survival of hereditary non-polyposis colorectal cancer patients compared with sporadic colorectal cancer patients

BACKGROUND

Patients with hereditary non-poliposys colorectal cancer (HNPCC) have better prognosis than sporadic colorectal cancer (CRC). Aim of our retrospective study was to compare the overall survival between sporadic CRC and HNPCC patients.

METHODS

We analyzed a cohort of 40 (25 males and 15 females) HNPCC cases with a hospital consecutive series of 573 (312 males and 261 females) sporadic CRC observed during the period 1970-1993. In 15 HNPCC patients we performed mutational analysis for microsatellite instability. Survival rates were calculated by Kaplan-Meier method and compared with log rank test.

RESULTS

The median age at diagnosis of the primary CRC was 46.8 years in the HNPCC series versus 61 years in sporadic CRC group. In HNPCC group 85% had a right cancer location, vs. 57% in the sporadic cancer group. In the sporadic cancer group 61.6% were early-stages cancer (Dukes' A and B) vs. 70% in the HNPCC group (p = ns). The crude 5-years cumulative survival after the primary CRC was 94.2% in HNPCC patients vs. 75.3% in sporadic cancer patients (p < 0.0001).

CONCLUSION

Our results show that overall survival of colorectal cancer in patients with HNPCC is better than sporadic CRC patients. The different outcome probably relates to the specific tumorigenesis involving DNA mismatch repair dysfunction.

Cost-effectiveness of surveillance programs for families at high and moderate risk of hereditary non-polyposis colorectal cancer

OBJECTIVES

Surveillance programs are recommended to both families at high risk (Amsterdam-positive families with known- and unknown mutation) and moderate risk (families not fulfilling all Amsterdam criteria) of colorectal cancer (CRC). Cost-effectiveness has so far only been estimated for the group at high risk. The aim of the present study is to determine cost-effectiveness of surveillance programs where families at both high and moderate risk of HNPCC participate.

METHODS

A decision analytic model (Markov model) is developed to assess surveillance programs where families at high and moderate risk of HNPCC are offered surveillance from age 25 and age 45, respectively. The model includes costs for all families referred to genetic counseling, including genetic risk assessment, mutation analysis, and surveillance in relevant families with or without known mutation, plus the costs related to any surgical treatment. The risk of metachronous CRC is also modeled.

RESULTS

Incremental costs per life year gained are estimated to be euro 980 when families at both high and moderate risk of HNPCC undergo surveillance (euro 508 for high risk and euro 1600 for moderate risk) and euro 1947 when the moderate risk group is evaluated genetically but not offered surveillance. Sensitivity analysis showed these findings to be robust, although cost-effectiveness can be improved in cases of more conservative referrals to genetic counseling.

CONCLUSIONS

The result for high risk families confirms the findings in similar studies. Somewhat surprisingly, cost-effectiveness improves when surveillance of the moderate risk groups are included in the decision model.

Cancer-associated genodermatoses: a personal history

Cancer-associated genodermatoses are a group of genetic disorders inherited in an autosomal-dominant fashion in which unique cutaneous findings are a reliable marker for the risk of developing internal malignancies. The historical, clinical and dermatopathological aspects of basal cell nevus syndrome, Muir-Torre syndrome, Cowden syndrome, Carney complex and Birt-Hogg-Dubé syndrome are reviewed in a personal and informal fashion. The latest advances in the molecular genetics of the disorders are also summarized.

Genotype-phenotype comparison of German MLH1 and MSH2 mutation carriers clinically affected with Lynch syndrome: a report by the German HNPCC Consortium

PURPOSE

Lynch syndrome is linked to germline mutations in mismatch repair genes. We analyzed the genotype-phenotype correlations in the largest cohort so far reported.

PATIENTS AND METHODS

Following standard algorithms, we identified 281 of 574 unrelated families with deleterious germline mutations in MLH1 (n = 124) or MSH2 (n = 157). A total of 988 patients with 1,381 cancers were included in this analysis.

RESULTS

We identified 181 and 259 individuals with proven or obligatory and 254 and 294 with assumed MLH1 and MSH2 mutations, respectively. Age at diagnosis was younger both in regard to first cancer (40 v 43 years; P < .009) and to first colorectal cancer (CRC; 41 v 44 years; P = .004) in MLH1 (n = 435) versus MSH2 (n = 553) mutation carriers. In both groups, rectal cancers were remarkably frequent, and the time span between first and second CRC was smaller if the first primary occurred left sided. Gastric cancer was the third most frequent malignancy occurring without a similarly affected relative in most cases. All prostate cancers occurred in MSH2 mutation carriers.

CONCLUSION

The proportion of rectal cancers and shorter time span to metachronous cancers indicates the need for a defined treatment strategy for primary rectal cancers in hereditary nonpolyposis colorectal cancer patients. Male MLH1 mutation carriers require earlier colonoscopy beginning at age 20 years. We propose regular gastric surveillance starting at age 35 years, regardless of the familial occurrence of this cancer. The association of prostate cancer with MSH2 mutations should be taken into consideration both for clinical and genetic counseling practice.

Survival of patients with ovarian cancer due to a mismatch repair defect

PURPOSE

Hereditary non-polyposis colorectal cancer (HNPCC, Lynch syndrome) is characterized by the development of cancer of the colorectum, endometrium and other cancers. Cancer of the ovaries (OC) has frequently been reported in HNPCC. Colorectal cancer associated with HNPCC has a better survival chance compared to sporadic colorectal cancer. It is yet unknown whether patients with OC from HNPCC families (OC-HNPCC) also have a better survival. Therefore, the aim of the study was to compare the survival between patients with OC-HNPCC and a control group.

METHODS

A total of 26 patients with OC were identified from the Dutch HNPCC Registry. A control group (52 cases) matched for age, stage and year of diagnosis was derived from the population-based Eindhoven Cancer Registry. Data on treatment were collected for all patients. Kaplan-Meier analysis was used to calculate the crude survival.

RESULTS

The mean age at diagnosis of OC-HNPCC was significantly lower than the age of sporadic OC (49.5 vs 60.9 years). Compared to sporadic OC, OC-HNPCC was diagnosed at an earlier stage. The survival rate was not significantly different between patients with OC-HNPCC and the controls with sporadic OC. The cumulative 5-year-survival rates were 64.2 and 58.1% respectively.

CONCLUSION

On the basis of our findings, we recommend to treat OC-HNPCC similar to sporadic OC.

Surveillance colonoscopy in individuals at risk for hereditary nonpolyposis colorectal cancer: an evidence-based review

PURPOSE

Surveillance colonoscopy plays an important role in the management of asymptomatic patients known to carry and suspected of carrying hereditary nonpolyposis colorectal cancer gene mutations. Although the shortest interval between surveillance examinations may seem to offer the most benefit to patients, excessive use of this procedure may have unwanted consequences. This study was designed to evaluate the evidence and make recommendations regarding the optimal frequency of surveillance colonoscopy and the age at which to initiate surveillance based on the best available evidence.

METHODS

MEDLINE was searched for all articles assessing surveillance colonoscopy from 1966 to 2004 by using the MESH terms "hereditary nonpolyposis colorectal cancer" and "screening." The evidence was systematically reviewed and a critical appraisal of the evidence was performed.

RESULTS

There are no randomized, controlled, clinical trials examining the frequency of surveillance colonoscopy in hereditary nonpolyposis colorectal cancer. Three cohort studies were identified for review. There is one cohort study of good quality that provides evidence that surveillance colonoscopy every three years in patients with hereditary nonpolyposis colorectal cancer reduces the risk of developing colorectal cancer and the risk of death. The two remaining cohort studies provide poor evidence on which to make a recommendation.

CONCLUSIONS

The best available evidence supports surveillance with complete colonoscopy to the cecum every three years in patients with hereditary nonpolyposis colorectal cancer (B recommendation). There is no evidence to support or refute more frequent screening. Further research is required to examine the potential harms and benefits of more frequent screening. However, given the potential for rapid progression from adenoma to carcinoma and missing lesions at colonoscopy, there is consensus that screening more frequently than every three years is required.

Cancer characteristics in Swedish families fulfilling criteria for hereditary nonpolyposis colorectal cancer

BACKGROUND & AIMS

The present study quantified the prevalence of families that fulfill the Amsterdam or Bethesda criteria for hereditary nonpolyposis colorectal cancer (HNPCC) in the whole Swedish population and investigated the extent to which tumors in the classified families are HNPCC-related.

METHODS

The families of the Swedish Family-Cancer Database with at least 4 generations (N = 566,877) were classified according to the Amsterdam and the Bethesda criteria. Survival methods were used to assess the risk of cancer in the classified families, the prognosis of cancer patients, and the risk of subsequent malignancies after colorectal adenomas and after colorectal/endometrial adenocarcinomas.

RESULTS

The Bethesda criteria identified 0.9% of all Swedish families and 11.2% of patients with colorectal cancer. Families that fulfilled the Bethesda criteria showed increased risks of cancer in the colorectum, endometrium, small bowel, ovary, stomach, bile ducts, renal pelvis, and ureter; members of Bethesda criteria families were at decreased risks of lung and cervical cancers. The prognosis of cancer in the ureter, renal pelvis, stomach, ovary, and colorectum, but not in the endometrium, was better in Bethesda criteria than in nonclassified families.

CONCLUSIONS

Most malignancies in the classified families reflect typical features of HNPCC (association with subsequent malignancies, accelerated adenoma-carcinoma sequence, and better survival). The data presented in this study should help to define surveillance strategies for members of families that fulfill the criteria for HNPCC testing.

Endoscopic management of familial colonic neoplasia

Heredity plays an important causative role in a large percentage of colorectal cancers. Clinical recognition of the hereditary polyposis syndromes, hereditary nonpolyposis colorectal cancer, and common familial colorectal cancer is essential because screening, surveillance, and treatment among affected individuals and their family members differs from that recommended for the general population. More intensive cancer screening and surveillance is required if premature death is to be avoided. Genetic testing is commercially available for most of the hereditary colorectal cancer syndromes and can greatly facilitate the management of patients if properly undertaken.

Microsatellite instability testing in colorectal carcinoma: choice of markers affects sensitivity of detection of mismatch repair-deficient tumors

PURPOSE

Microsatellite instability (MSI) is found in 10% to 15% of sporadic colorectal tumors and is usually caused by defects in DNA mismatch repair (MMR). In 1997, a panel of microsatellite markers including mononucleotide and dinucleotide repeats was recommended by a National Cancer Institute workshop on MSI. We investigated the relationship between instability of these markers and MMR protein expression in a cohort of sporadic colorectal cancer patients.

EXPERIMENTAL DESIGN

Paraffin sections of normal and tumor tissue from 262 colorectal cancer patients were examined for MSI status by PCR amplification and for MMR protein expression using antibodies against hMLH1, hPMS2, hMSH2, and hMSH6.

RESULTS

Twenty-six (10%) of the patients studied had tumors with a high level of MSI (MSI-H). The frequencies of MSI were the same in African-American and Caucasian patients. Each of the MSI-H tumors had mutations in both mononucleotide and dinucleotide repeats and had loss of MMR protein expression, as did two tumors that had low levels of MSI (MSI-L). These two MSI-L tumors exhibited mutations in mononucleotide repeats only, whereas eight of the other nine MSI-L tumors had mutations in just a single dinucleotide repeat. There was not a statistically significant difference in outcomes between patients whose tumors were MMR-positive or MMR-negative, although there was a slight trend toward improved survival among those with MMR-deficient tumors.

CONCLUSIONS

The choice of microsatellite markers is important for MSI testing. Examination of mononucleotide repeats is sufficient for detection of tumors with MMR defects, whereas instability only in dinucleotides is characteristic of MSI-L/MMR-positive tumors.

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

AIM: To describe systematically the clinical characteristics and phenotype of HNPCC families and the prevalence of HNPCC in the general population of CRC patients in China.

METHODS: HNPCC kindreds and CRC patients were from two sources. One was that we consecutively investigated kindreds and patients by ourselves. And the other was the published Chinese and foreign literature related to Chinese HNPCC syndrome. There were 142 HNPCC families fulfilling AC I and/or AC II including 57 families with detailed data, and 3874 general primary CRC patients in all. All statistical tests were two-sided.

RESULTS: In AC I families, the number of Lynch syndrome I and II families were 25 (47.2%) and 28 (52.8%) respectively. There were 215 patients (82.4%) with CRC, 67 patients (25.7%) with extracolonic cancer and 50 patients (19.2%) with multiple primary cancers. In all CRC patients, multiple primary CRC were in 41 patients (19.1%), and the first-CRC was right-sided colorectal cancer in 143 patients (66.5%) and rectal cancer in 44 patients (20.5%). 8.8% and 19.2% of the first cancer were CRC and extracolonic cancers. Among those patients whose first cancer was CRC, 66.8% and 19.9% were right-sided colorectal cancer and rectal cancer, respectively. The similar results were found in AC II families. Normal distribution was only found in the distribution of the age of diagnosis of the first cancer in both AC I families (coefficient of skewness: u = 0.81, 0.20<0.40<P<0.50; coefficient of kurtosis: u = 1.13, 0.20<P<0.40, α = 0.20) and AC II families (coefficient of skewness: u = 0.63, P>0.5>0.20; coefficient of kurtosis: u = 0.84, 0.20<0.40<P<0.50, α = 0.20), but not found in the distribution of the age of diagnosis of the first CRC. When patients with HNPCC-associated cancer suffered from the first malignant tumor in HNPCC families diagnosed by AC I and AC II, the mean age and median age were 45.1±12.7 years and 44.0 years, 45.2±12.7 years and 44.5 years, respectively. The median age of diagnosis of the first tumor of the patients in the later generation was younger than that in the previous generation. Many extracolonic cancers were found to be associated with HNPCC syndrome. Gastric cancer was the most frequent extracolonic cancer followed by endometrial cancer and hepatocarcinoma. In general population of CRC patients, the prevalence of HNPCC diagnosed by AC I and AC II were 1.3% and 2.2%, respectively.

CONCLUSION: The clinical phenotype and prevalence of Chinese HNPCC syndrome are similar to those of Europeans and Americans. Gastric cancer is the most common extracolonic malignant tumor. The age of diagnosis of the first malignant tumor tends to be increasingly younger in patients with HNPCC-related tumors.

Fractional Genomic Alteration Detected by Array-Based Comparative Genomic Hybridization Independently Predicts Survival after Hepatic Resection for Metastatic Colorectal Cancer

PURPOSE

Although liver resection is the primary curative therapy for patients with colorectal hepatic metastases, most patients have a recurrence. Identification of molecular markers that predict patients at highest risk for recurrence may help to target further therapy.

EXPERIMENTAL DESIGN

Array-based comparative genomic hybridization was used to investigate the association of DNA copy number alterations with outcome in patients with colorectal liver metastasis resected with curative intent. DNA from 50 liver metastases was labeled and hybridized onto an array consisting of 2,463 bacterial artificial chromosome clones covering the entire genome. The total fraction of genome altered (FGA) in the metastases and the patient's clinical risk score (CRS) were calculated to identify independent prognostic factors for survival.

RESULTS

An average of 30 +/- 14% of the genome was altered in the liver metastases (14% gained and 16% lost). As expected, a lower CRS was an independent predictor of overall survival (P = 0.03). In addition, a high FGA also was an independent predictor of survival (P = 0.01). The median survival time in patients with a low CRS (score 0-2) and a high (> or =20%) FGA was 38 months compared with 18 months in patients with a low CRS and a low FGA. Supervised analyses, using Prediction Analysis of Microarrays and Significance Analysis of Microarrays, identified a set of clones, predominantly located on chromosomes 7 and 20, which best predicted survival.

CONCLUSIONS

Both FGA and CRS are independent predictors of survival in patients with resected hepatic colorectal cancer metastases. The greater the FGA, the more likely the patient is to survive.

APC genotype is not a prognostic factor in familial adenomatous polyposis patients with colorectal cancer

PURPOSE

Several studies have shown that the clinical phenotype of patients with familial adenomatous polyposis is influenced by the position of the associated germline mutation in the APC gene. The aim of this work was to assess whether the site of the APC mutation may also predict the survival of familial adenomatous polyposis patients with a confirmed diagnosis of colorectal cancer.

METHODS

A total of 387 familial adenomatous polyposis patients with colorectal cancer were examined. Of these, 287 (74 percent) belonged to families with an identified mutation, whereas 100 (26 percent) were from families in which no detectable APC mutation had been found by standard screening methods. The subjects were subdivided into four groups, according to the presence and localization of the identified mutation: with mutation before (a), at (b), or beyond codon 1309 (c), and without identified mutation (d).

RESULTS

The cumulative five-year survival estimate of all cases included in the study was 0.56 (95 percent confidence interval, 0.51-0.61). No difference was observed in survival probability among patients from families with mutations before (0.56; 95 percent confidence interval, 0.49-0.63), at (0.58; 95 percent confidence interval, 0.43-0.72), or beyond (0.52; 95 percent confidence interval, 0.31-0.73) codon 1309 or those from families that were mutation negative (0.58; 95 percent confidence interval, 0.48-0.68) (log-rank test, P = 0.9). Survival analysis did not reveal any significant advantage for patients carrying a mutation in a specific region of the APC gene, after adjustment for age, gender, site, and stage.

CONCLUSION

These data do not support the hypothesis that APC mutation may influence the outcome of familial adenomatous polyposis cases affected by colorectal cancer.

Cancer genetics in primary care

The cloning of two major breast cancer susceptibility genes, BRCA1 and BRCA2, in 1994 and 1995 and the subsequent development of commercial genetic testing has brought hereditary cancer genetics into the public eye. In addition to DNA-based genetic testing, new strategies and treatments have been developed to provide accurate assessment of cancer risk and to reduce the chances of cancer developing in the future. This increasing scientific and public attention has prompted some cancer patients and their families to find out whether they "have the cancer gene" and has placed more responsibility on primary care clinicians to identify people who should be referred for specialized services of hereditary cancer genetics.

An economic viewpoint on alternative strategies for identifying persons with hereditary nonpolyposis colorectal cancer

PURPOSE

There is uncertainty regarding the optimal strategy for identifying mutation carriers among those with hereditary nonpolyposis colorectal cancer (HNPCC).

METHODS

We used decision analysis to compare the cost-effectiveness of 4 strategies among those with newly diagnosed colon cancer: (1) clinical and family history followed by microsatellite instability testing and germline testing (Bethesda guidelines); (2) universal microsatellite instability testing; (3) germline testing of those who meet clinical and family history criteria; and (4) universal germline testing.

RESULTS

The added cost per year of life saved (YLS) for each strategy was as follows: (1) 11,865 US dollars/YLS, (2) 35,617 US dollars/YLS, (3) 49,702 US dollars/YLS, and (4) 267,548 US dollars/YLS.

CONCLUSIONS

The Bethesda guidelines are the most cost-effectiveness approach to screen persons for HNPCC.

Mutation analysis of the MLH1, MSH2 and MSH6 genes in patients with double primary cancers of the colorectum and the endometrium: a population-based study in northern Sweden

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disorder that predisposes to predominantly colorectal and endometrial cancers due to germline mutations in DNA mismatch repair genes, mainly MLH1, MSH2 and in families with excess endometrial cancer also MSH6. In this population-based study, we analysed the mutation spectrum of the MLH1, MSH2 and MSH6 genes in a cohort of patients with microsatellite unstable double primary tumours of the colorectum and the endometrium by PCR, DHPLC and sequencing. Fourteen of the 23 patients (61%) had sequence variants in MLH1, MSH2 or MSH6 that likely affect the protein function. A majority (10/14) of the mutations was found among probands diagnosed before age 50. Five of the mutations (36%) were located in MLH1, 3 (21%) in MSH2 and 6 (43%) in MSH6. MSH6 seem to have larger impact in our population than in other populations, due to a founder effect since all of the MSH6 families originate from the same geographical area. MSH6 mutation carriers have later age of onset of both colorectal cancer (62 vs. 51 years) and endometrial cancer (58 vs. 48 years) and a larger proportion of endometrial cancer than MLH1 or MSH2 mutation carriers. We can conclude that patients with microsatellite unstable double primary cancers of the colorectum and the endometrium have a very high risk of carrying a mutation not only in MLH1 or MSH2 but also in MSH6, especially if they get their first cancer diagnosis before the age of 50.

Prognostic significance of microsatellite instability in curatively resected adenocarcinoma of the small intestine

Adenocarcinoma of the small intestine (ACSI) is a rare condition with few studies addressing follow-up and prognosis. Tumors of 35 patients with curative resection of an ACSI were retrospectively analyzed by immunohistochemistry: p53, hMLH1, hMSH2 and hMSH6 and microsatellite instability (MSI): BAT-26, BAX, TGF-beta RII. With a median follow up of 6.1 years, the median cancer-specific survival (CSS) was 36.2 months. Patients who were highly instable (MSI-H) (n=10) had a CSS of 49.6 months in contrast to patients with stable tumors (23.2 months) (P=0.010). Additionally, a low tumor stage according to UICC and MSI-H were shown to be independent factors (P=0.005 and P<0.001) for an increased survival in multivariate analysis. Therefore, it is suggested that analysis of the MSI status might prove useful in discerning prognosis within cancers of the same stage.

The reliability of immunohistochemistry as a prescreening method for the diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC)--results of an international collaborative study

Hereditary nonpolyposis colorectal cancer syndrome (HNPCC) is an autosomal dominant condition accounting for 2-5% of all colorectal carcinomas as well as a small subset of endometrial, upper urinary tract and other gastrointestinal cancers. An assay to detect the underlying defect in HNPCC, inactivation of a DNA mismatch repair enzyme, would be useful in identifying HNPCC probands. Monoclonal antibodies against hMLH1 and hMSH2, two DNA mismatch repair proteins which account for most HNPCC cancers, are commercially available. This study sought to investigate the potential utility of these antibodies in determining the expression status of these proteins in paraffin-embedded formalin-fixed tissue and to identify key technical protocol components associated with successful staining. A set of 20 colorectal carcinoma cases of known hMLH1 and hMSH2 mutation and expression status underwent immunoperoxidase staining at multiple institutions, each of which used their own technical protocol. Staining for hMSH2 was successful in most laboratories while staining for hMLH1 proved problematic in multiple labs. However, a significant minority of laboratories demonstrated excellent results including high discriminatory power with both monoclonal antibodies. These laboratories appropriately identified hMLH1 or hMSH2 inactivation with high sensitivity and specificity. The key protocol point associated with successful staining was an antigen retrieval step involving heat treatment and either EDTA or citrate buffer. This study demonstrates the potential utility of immunohistochemistry in detecting HNPCC probands and identifies key technical components for successful staining.

Mismatch repair and response to DNA-damaging antitumour therapies

Most antitumour therapies damage tumour cell DNA either directly or indirectly. DNA damage responses, and particularly DNA repair, influence the outcome of therapy. Because DNA repair normally excises lethal DNA lesions, it is intuitive that efficient repair will contribute to intrinsic drug resistance. Indeed, in certain circumstances reduced levels of DNA nucleotide excision repair are associated with a good therapeutic outlook (Curr Biol 9 (1999) 273). A paradoxical relationship between DNA mismatch repair (MMR) and drug sensitivity has been revealed by model studies in cell lines. This suggests that connections between MMR and tumour therapy might be more complex. Here, we briefly review how MMR deficiency can affect drug resistance and the extent to which loss of MMR is a prognostic factor in certain cancer therapies. We also consider how the inverse relationship between MMR activity and drug resistance might influence the development of treatment-related malignancies which are increasingly linked to MMR defects.

Effect of H(2)O(2) on cell cycle and survival in DNA mismatch repair-deficient and -proficient cell lines

Patients who develop tumors with Lynch syndrome, which is caused by mutational inactivation of the DNA mismatch repair (MMR) system, have a relatively favorable prognosis compared to patients who develop sporadic tumors. Paradoxically, DNA MMR-deficient cells are resistant to many chemotherapeutic agents, and are capable of bypassing the G2/M checkpoint in vitro. Colon cancers that develop in the setting of Lynch syndrome show an abundant recruitment of immune cells into tumor tissues, which might be expected to increase oxyradical formation, and make the tumor cells more vulnerable to cell death. We examined the chemosensitivity and cell cycle response to oxidative stress in several MMR-deficient (HCT116, SW48, and DLD1) and -proficient (CaCo2, SW480, and HT29) colorectal cancer cell lines. H(2)O(2) induced a G2/M cell cycle arrest in both MMR deficient and proficient cell lines, however MMR-deficient cell lines were more sensitive to H(2)O(2) toxicity, and the response was more prolonged in MMR-deficient cells. Interestingly, human MutL-homologue (hMLH1-)defective HCT116 and hMLH1-restored HCT116+ch3 cell lines responded to H(2)O(2) with the same degree of G2/M arrest. The survival response of HCT116+ch3 was nearly identical to that of hMLH1-defective HCT116+ch2, although better than the response observed in HCT116 cells. In conclusion, greater cellular sensitivity and G2/M arrest in response to oxidative stress in MMR-deficient colorectal cancer cells could be one of the reasons for the more favorable prognosis seen in patients with Lynch syndrome. However, this sensitivity appears not to be a direct result of a deficient MMR function, but is more likely attributable to spectrum of target gene mutations that occurs in MMR-deficient tumors.

Hereditary polyposis syndromes and hereditary non-polyposis colorectal cancer

Colorectal cancer due to hereditary syndromes comprises approximately 5% of the overall colorectal cancer burden. Conditions fall into two distinct categories, the polyposis syndromes and hereditary non-polyposis colorectal cancer. It is important for the clinician to have a working knowledge of both as screening and surveillance recommendations differ significantly from those applicable to the general population. The polyposis syndromes include familial adenomatous polyposis, Peutz-Jeghers syndrome, juvenile polyposis, and Cowden syndrome. For each condition, a review of both the intestinal and extra-intestinal clinical findings is presented as well as the genetic basis, genetic testing, screening, surveillance and treatment options. As genetic testing for several of these conditions has recently become both commercially available and standard practice, special attention is given to indications and strategies for genetic testing in hereditary colorectal cancer syndromes.

The clinical importance and prognostic implications of microsatellite instability in sporadic cancer

AIMS

The genetic abnormality known as microsatellite instability (MSI), first identified in colorectal cancer in 1993, has subsequently been recognised in other malignancies. These cancers are caused by a defect in the nuclear mismatch repair system, allowing mutations to accumulate with every cellular division. Hereditary Non Polyposis Colon Cancers (HNPCC) and associated malignancies demonstrating MSI have a unique histological appearance, improved prognosis and altered response to chemotherapy and radiotherapy. This review examines the incidence of MSI and its clinical significance in commonly occurring solid malignancies.

METHOD

A medline based literature search was performed using the key words 'Microsatellite Instability' and the name of the specific malignancy being investigated. Additional original papers were obtained from citations in those articles identified in the original medline search.

RESULTS

MSI has been detected in many solid malignancies although the definition of instability applied has been variable. It is most commonly found in sporadic malignancies that also occur in the HNPCC syndrome such as colorectal, stomach, endometrial and ovarian cancer. MSI may impart a favorable prognosis in colorectal, gastric, pancreatic and probably oesophageal cancers but a poor prognosis in non small cell lung cancer. In clinical studies colorectal cancers demonstrating MSI respond better to chemotherapy while in vitro studies using MSI positive cell lines show resistance to radiotherapy and chemotherapy.

CONCLUSION

MSI may be a useful genetic marker in prognosis and could be an influential factor in deciding treatment options. However, in many cancers its significance remains unclear and more evaluation is required.

Clinical characteristics and diagnosis of patients with hereditary nonpolyposis colorectal cancer

AIM: To study the clinical characteristics of hereditary nonpolyposis colorectal cancer (HNPCC) in the Chinese population and discuss the identification and management of the patients with HNPCC.

METHODS: A series of 140 patients with colorectal cancers (CRC) and HNPCC associated tumors from 30 families fulfilling the Amsterdam criteria were analyzed.

RESULTS: A total of 118 patients had CRC. Average age at diagnosis of the first CRC was 45.7 years, 56.8% and 23.4% of the first CRC were located proximal to the splenic flexure and in the rectum respectively. Twenty-three (19.5%) had synchronous and metachronous CRC. Twenty-seven patients were found to have extracolonic tumors. Gastric carcinoma was the most common tumor type in our series (44.4%).

CONCLUSION: The frequency of HNPCC was 2.6% in our series of patients. The main features are an excess of early onset with a propensity to involve the proximal colon, and high frequency of multiple foci. Management and surveillance for these patients should be different from sporadic CRC. Contrary to American and European reports, gastric cancer seems more frequent than endometrial cancer in Chinese. It is necessary to formulate a new HNPCC criterion for Chinese patients.

Survival analysis of endometrial carcinoma associated with hereditary nonpolyposis colorectal cancer

Endometrial carcinoma (EC) is the most common extracolonic tumor associated with hereditary nonpolyposis colorectal cancer (HNPCC). HNPCC increases the risk of EC compared to the general population. Patients with HNPCC have a better prognosis than patients with common sporadic colorectal cancer. It is unknown, however, whether the survival rate of HNPCC-associated EC is higher than that of sporadic EC. The aim of our study was to compare the survival rates of HNPCC-associated EC with sporadic EC. From the registry of the Netherlands Foundation for Hereditary Tumors, 50 patients with HNPCC-associated EC from 46 families harboring a germline mutation or fulfilling the Amsterdam Criteria II were age- and stage-matched with 100 patients with sporadic EC registered in the Eindhoven Cancer Registry in the Netherlands. Survival rates were analyzed. The overall 5-year cumulative survival rates for patients with HNPCC-associated EC was 88% and 82% for patients with sporadic EC (p = 0.59). In Stages IA, IB and IC, the survival rates of patients with HNPCC-associated EC and sporadic EC were 92% and 91%, respectively (p = 0.90). In Stages IIIA and IIIC, the survival rates for HNPCC-associated EC and sporadic EC were 72% and 50%, respectively (p = 0.38). Furthermore, there was no significant difference in the distribution of tumor histologic subtypes in the study and control groups (p = 0.55). The outcomes in survival in EC in the general population and in women from families with HNPCC do not differ significantly. These results may have important implications in our understanding of EC and the role of early screening.

Pathogenesis and clinical management of hereditary non-polyposis colorectal cancer

BACKGROUND

Hereditary non-polyposis colorectal cancer (HNPCC) is an inherited genetic condition associated with microsatellite instability; it accounts for around 5 per cent of all cases of colorectal cancer. This review examines recent data on management strategies for this condition.

METHODS

A Medline-based literature search was performed using the keywords 'HNPCC' and 'microsatellite instability'. Additional original papers were obtained from citations in articles identified by the initial search.

RESULTS AND CONCLUSION

The Amsterdam criteria identify patients in whom the presence of an inherited mutation should be investigated. Those with a mutation should be offered counselling and screening. The role of prophylactic surgery has been superseded by regular colonoscopy, which dramatically reduces the risk of colorectal cancer. Screening for extracolonic malignancy is also advocated, but the benefits are uncertain. Chemoprevention may be of value in lowering the incidence of bowel cancer in affected patients, but further studies are required.

Hereditary non-polyposis colorectal cancer (HNPCC): phenotype-genotype correlation between patients with and without identified mutation

Affected members of hereditary non-polyposis colorectal cancer (HNPCC) families develop colorectal cancer at an early age (mean 45 yr) and frequently get extracolonic cancers particularly in the uterus, urinary tract, and small intestine. They have a high risk of developing more than one primary colorectal cancer if not treated with subtotal colectomy at first operation and have more frequent right-sided colon cancers and less frequent rectum cancers, compared to patients with sporadic colorectal cancer. We have screened 31 families fulfilling the Amsterdam criteria and 54 families with a colorectal cancer clustering but not fulfilling the Amsterdam criteria for mutations in MLH1 and MSH2 by direct sequencing, and detected a mutation in 61% of the Amsterdam positive families but only in 15% of the Amsterdam negative families. Genotype-phenotype correlation was compared between 141 affected individuals with an identified mutation and 78 affected individuals from Amsterdam positive families in which a mutation was not identifiable in MLH1 or MSH2. In the affected persons with identified mutations, all expected phenotypic traits were represented, whereas affected persons in whom no mutation was detected fell into two clearly distinguishable subgroups. The minor subgroup, in which no mutation was identified, generally had the same characteristics as found in affected persons with identified mutations. The major subgroup differed significantly in clinical features and exhibited phenotypic traits similar to those found in late-onset families, including abundance of rectal cancer, few HNPCC-related cancers, lower frequency of multiple colorectal cancers, and later age at onset. Finally, for six missense mutations and one single codon deletion, the pathogenic potential was evaluated by domain localization, lod score calculation or segregation analysis when possible, and mutation-induced biochemical change. The results indicate that the majority of missense mutations are pathogenic, although further characterization by functional assays is necessary before implementation in predictive testing programs.

Is reduced expression of mismatch repair genes MLH1 and MSH2 in patients with sporadic colorectal cancer related to their prognosis?

The majority of mutations in hereditary nonpolyposis colon carcinoma (HNPCC) patients affect the mismatch-repair genes (MMRG) MLHI and MSH2. In addition, mutations of these genes were found in about 15% of sporadic colorectal carcinomas which appear to be related to microsatellite instability (MSI). However, mutations in MMRG were not found in all MSI-positive carcinomas, but MMRG mutations may be relevant for the assessment of tumor characteristics and patients' prognosis. Therefore, we investigated the relationship between expression of MMRG, tumor biology and patients' survival. In 127 patients with sporadic colorectal carcinomas and a minimum of 5 years follow-up after curative surgery immunohistochemical detection of MLHI and MSH2 was analyzed semiquantitatively. Lost expression of MLHI has been found in tumor specimens from 10 patients, whereas MSH2 expression was missing in 5 patients. This reduced expression did not correlate with tumor stage, lymph node involvement, grading or tumor invasion into blood vessels. However, a significant correlation was found for lymphovascular invasion (P = 0.02) and localization within the colorectum (P = 0.003) in MLH1-negative carcinomas. In addition, although there was a clear tendency for longer overall survival (72 vs. 63 months) for patients with MLH1-negative carcinomas, significant differences for overall and recurrence-free survival were not seen. In conclusion of our results and a critical review of literature, the prognostic importance of the MMR genes in sporadic colorectal carcinomas remains controversial.

Hereditary nonpolyposis colorectal cancer in young colorectal cancer patients: high-risk clinic versus population-based registry

BACKGROUND & AIMS

Early onset colorectal cancer (CRC) is an important feature of hereditary nonpolyposis colorectal cancer (HNPCC). We sought to compare rates of genetically defined HNPCC among individuals with early onset CRC drawn from a high-risk clinic and a population-based cancer registry.

METHODS

Probands with CRC diagnosed before 36 years of age were enrolled from a high-risk CRC clinic at the University of California, San Francisco (UCSF), and a population-based Kaiser Permanente (KP) Health Plan cancer registry. Probands provided cancer family histories and tumors for microsatellite instability (MSI) testing and MSH2/MLH1 protein immunostaining. Germline MSH2 and MLH1 mutational analysis was performed.

RESULTS

Forty-three probands were enrolled from UCSF and 23 from KP. The UCSF and KP probands had similar median age of onset of CRC (30 vs. 31 years) and the percentage with any personal or family history of another HNPCC-related cancer (70% vs. 74%). However, 28 of 40 (70%) of the UCSF tumors were MSI-H compared with 6 of 18 (33%) of KP tumors (P = 0.01), and 13 germline MSH2 or MLH1 mutations were found in the UCSF group compared with 0 in the KP group (P = 0.0001). In a multivariate analysis, institution (P = 0.002) and the total number of colorectal cancers in the family (P = 0.0001) were independent predictors of MSH2 or MLH1 mutation.

CONCLUSIONS

Family history of cancer is an important feature of HNPCC, even among individuals with early onset CRC. Caution must be undertaken when extrapolating data regarding HNPCC from high-risk clinic populations to the general population.

Use of microsatellite analysis in young patients with colorectal cancer to identify those with hereditary nonpolyposis colorectal cancer

BACKGROUND AND OBJECTIVES

The frequency of microsatellite instability (MSI) in young patients with colorectal cancer was evaluated, including reexamination of the medical and family history of each patient, and interviews with the patients to determine any possible new occurrence of hereditary nonpolyposis colorectal cancer (HNPCC) in the patients themselves or their family members.

METHODS

Fifty-three young patients (younger than 40 years of age) with colorectal cancer were selected and investigated. DNA was extracted from paraffin sections and microsatellite analysis was performed.

RESULTS

The frequency of MSI among the young patients with colorectal cancer was 50.9%, which was significantly higher than the rate of 12-21% noted in older patients with colorectal cancer (P < 0.001). For the 24 young patients with colorectal cancer who did not have MSI, only one case of HNPCC kindred and two cases with a family history of cancer were identified. In contrast, among the 20 young patients with colorectal cancer who had MSI, five cases of HNPCC kindred, two cases with metachronous patients with colorectal cancer, and three cases with a family history of cancer were identified.

CONCLUSION

Our results suggest that a defect in the DNA mismatch repair system may play some role in carcinogenesis in young patients with colorectal cancer. Microsatellite analysis and subsequent interviews regarding medical and family history are useful tools for efficiently identifying possible cases of HNPCC among young patients with colorectal cancer.

Patient accuracy of reporting on hereditary non-polyposis colorectal cancer-related malignancy in family members

BACKGROUND

The cancer family history is important in identifying individuals with hereditary non-polyposis colorectal cancer (HNPCC). The accuracy of a suspected HNPCC family history reported by patients with colorectal cancer was evaluated.

METHODS

This was a prospective population-based study including consecutive patients with colorectal cancer. A questionnaire covering the occurrence of malignancy among relatives was completed.

RESULTS

A total of 1200 patients with colorectal cancer completed the questionnaire. Fulfilment of Amsterdam criteria I or II according to the patients' reports was rejected in three of 14 cases (false-positive rate 21 per cent). Furthermore, seven of 18 probands whose families met the Amsterdam criteria I or II after verification were identified by further exploration in families who, according to the probands, met weaker criteria (false-negative rate 39 per cent).

CONCLUSION

The present study suggests that family studies on HNPCC are not reliable unless the diagnoses of family members are verified from official sources. If endoscopic screening is offered entirely on the basis of unverified information from patients with colorectal cancer, there is a risk that a large proportion of the families will not be offered relevant surveillance.