Survival analysis in families affected by hereditary non-polyposis colorectal cancer

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.

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.

Lifestyle and family history influence cancer prognosis in Brazilian individuals

The aim of this research was to study prognostic parameters of CRC by analyzing clinical and pathological variables associated with cancer patients at a northeastern Brazilian Hospital. This was a retrospective study evaluating CRC-diagnosed patients across a 10-year period (1995-2005) at Dr. Luiz Antônio Hospital in Natal, RN, Brazil. Data were collected from patients' medical files. A total of 358 patients were included over the 10-year period. The average age at diagnosis was 58.8 years (S.D.=15.26), 48.3% of the patients were males and 51.7% were females. Alcohol consumption significantly increased the chance of dying (p<0.023) from colorectal cancer; this increased risk of death was approximately 71%, compared to 52.2% of the non-alcoholics. In addition, tobacco increased the chance of developing high TNM stage tumors (level III, IV; p<0.001). Another risk factor for increased mortality was a family history for colorectal cancer (p<0.002). Our analysis found that patients with an unhealthy lifestyle and/or family history of colorectal cancer were more likely to develop advanced stage colorectal cancer and to have a poor disease prognosis compared to patients with healthy lifestyle and/or sporadic colorectal cancer. These data suggest that a mass screening program should be implemented in northeastern Brazil in order to better prevent and treat colorectal cancer.

Reduced expression of MUTYH with suppressive activity against mutations caused by 8-hydroxyguanine is a novel predictor of a poor prognosis in human gastric cancer

The MUTYH gene encodes a DNA glycosylase that can initiate the excision repair of adenine mispaired with 8-hydroxyguanine (8OHG) and is responsible for a susceptibility to multiple colorectal adenomas and carcinomas. To determine whether the MUTYH gene is involved in gastric carcinogenesis, we first examined the expression level of MUTYH in gastric cancer. The reduced expression of MUTYH mRNA transcript was detected in both gastric cancer cell lines and primary gastric cancers using qRT-PCR analysis. Immunohistochemical analysis also showed a significant reduction in MUTYH protein expression in gastric cancer, compared with non-cancerous gastric epithelium (immunohistochemical score, 175.5 ± 43.0 versus 281.5 ± 24.8; p < 0.0001). Among the gastric cancers, the MUTYH expression level was significantly associated with the histopathology (p < 0.0001) and the pT stage (p < 0.001). The outcome of patients with gastric cancer exhibiting low MUTYH expression was significantly worse than the outcome of patients with gastric cancer exhibiting high MUTYH expression (p = 0.0007, log-rank test) and a multivariate analysis revealed that reduced MUTYH expression was an independent predictor of a poor survival outcome among the gastric cancer patients (hazard ratio, 1.865; 95% confidence interval, 1.028-3.529; p = 0.0401). We next compared the functional effects of MUTYH on gastric cancer cells, based on their MUTYH expression levels. MUTYH-over-expressing stable clones of the gastric cancer cell line AGS showed: (a) higher DNA cleavage activity towards adenine:8OHG mispair-containing substrates; (b) higher suppressive activity against mutations caused by 8OHG in a supF forward mutation assay; and (c) higher suppressive activity for cellular proliferation than empty vector-transfected AGS clones. These results suggested that MUTYH is a suppressor of mutations caused by 8OHG in gastric cells and that its reduced expression is associated with a poor prognosis in gastric cancer.

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.

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.

Colorectal cancer in HNPCC: cumulative lifetime incidence, survival and tumour distribution. A report of 121 families with proven mutations

Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant condition caused by inactivating mutations of DNA mismatch repair (MMR) genes. An accurate estimation of colorectal cancer risk for mutation carriers is essential for counselling and rationalizing screening programmes. Families were referred on the basis of clinical criteria. Tumour immunohistochemistry and microsatellite testing were performed. Appropriate patients underwent sequencing of all relevant exons of the MMR genes. Proven and obligate mutation carriers and first-degree relatives (FDRs) with an HNPCC spectrum cancer were considered mutation carriers, as were a proportion of untested, unaffected FDRs based on the proportion of unaffected relatives testing positive in each age group. The cumulative lifetime risk was calculated by Kaplan-Meier analysis. Three hundred and forty-one colorectal cancers in 839 proven, obligate, or assumed mutation carriers were analysed. The cumulative risk to age 70 years for all mutation carriers combined was 50.4% (95% CI 47.8-52.9). The cumulative risk in males was 54.3% (95% CI 50.7-57.8), which was significantly higher than in females (log rank p = 0.02) who had a risk of 46.3% (95% CI 42.8-49.9). These penetrance estimates from HNPCC families attending high-risk clinics have been corrected for ascertainment bias and are appropriate risks for those referred to a high-risk clinic. Current colonoscopic screening guidelines are appropriate.

Prognostic value of BRCA1 mutations in familial breast cancer patients affected by a second primary cancer

The aim of this prospective study is to assess the prognostic value of BRCA1 mutations in familial breast cancer patients affected by a second primary cancer. The study group comprised 19 women having multiple primary breast cancers (breast-breast, breast-other primary) who were either BRCA1 mutation carriers, or not. Appearance of a second primary cancer was recognised as the event and survival and second primary free cancer survival was calculated from the date of diagnosis to the secondary primary cancer. The results of this study show that the event free survival of women with familial breast cancer affected by a second primary cancer, who are BRCA1 mutation carriers is better, compared with women from the general population with breast cancer selected for second primary cancer sites and all second primary sites -- P = 0.009 and P = 0.0078 respectively. In contrast, the event free survival of women with breast cancer affected by a second primary cancer, without a breast cancer family history, who are not BRCA1 mutation carriers is the same, as for women from the general population with breast cancer selected for second primary cancer sites and all second primary sites -- P = 0.6417 and P = 0.4859 respectively. The median time from diagnosis of the first to second primary cancer in the mutation carrying, and non-carrying, groups was 8,7 and 1,9 years respectively. In the study group, the highest event free survival rates had been observed among those carrying the said mutations -- 66.7% at 5 years, and 33.3% at 10 years -- in contrast with those not carrying the mutations, with rates of 30.8% and 15.4% respectively.

Inverse effects of mucin on survival of matched hereditary nonpolyposis colorectal cancer and sporadic colorectal cancer patients

PURPOSE

To compare survival and histologic features of hereditary nonpolyposis colorectal cancer (HNPCC; Lynch syndrome) cases to well-matched sporadic colon cancers from the same patient population.

EXPERIMENTAL DESIGN

Between January 1995 and March 2002, a total of 5,138 consecutive patients underwent resection of primary colorectal adenocarcinoma in a single institution. According to the Amsterdam criteria, 56 HNPCC patients were matched to 147 sporadic colorectal cancer (SCRC) with no family history of cancer and with the same gender, tumor location, and age within 3 years. Immunohistochemical analyses were done for MUC1, MUC2, MUC3, and MUC5AC.

RESULTS

The HNPCC group had a marginally significantly better long-term outcome than the SCRC group (P = 0.058). The trend disappeared after adjustment by tumor-node-metastasis stage in a Cox model (P = 0.774). We noted a difference of >50% in the 5-year cancer-specific survival rates of HNPCC- and SCRC-mucinous groups (92% versus 31%, P = 0.0003). Interaction between mucin and HNPCC and its effects on survival were further confirmed by comparing the Cox models with and without interaction terms (hazard ratio, 0.1; P = 0.034 with adjusting stage). Patients with tumors showing dual expression of mucin and MUC1, which appeared in 11% of those with HNPCC and 50% of those with SCRC, had a lower 5-year cancer-specific survival rate than patients without (30% versus 60%; P = 0.004 by log-rank test; P = 0.039 with adjustment for tumor-node-metastasis stage).

CONCLUSIONS

These results suggest that mucin has an inverse effect on survival in patients with HNPCC and SCRC, which might be partly explained by a lower prevalence of MUC1 expression in the mucinous HNPCC group than in the SCRC groups.

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 from colorectal carcinoma in HNPCC families as compared to the general population in Lithuania--initial results

BACKGROUND

Colorectal cancer in HNPCC appears to have a better prognosis than sporadic colorectal cancer. Selection bias, screening, early intervention and treatment hamper efforts to confirm such a hypothesis.

AIM

To evaluate survival rates in Lithuanian HNPCC patients with colorectal cancer and compare them with survival rates of sporadic cases arising from the general population.

PATIENTS AND METHODS

The study group consisted of 8 patients from 6 Hereditary non-polyposis colorectal carcinoma (HNPCC) families, 3 patients had HMSH2 and 5 patients had HMLH1 mutations, who were diagnosed between 1995 and 1999. HNPCC patients characteristic (age and stage) were used to trace the records of the Cancer Registry at the same period to identify the cases corresponding the required criteria. Above 263 patients were found--106 at stage II and 157 at stage III.

RESULTS

The 10-year survival was 87.5% in the HNPCC study group compared with only 44.8% in the general population group. Patients with the MSH2 gene mutation were at a greater risk of developing a second primary cancer independent from any cancer prevention and screening programs. Survival rates were also prolonged even with a greater numbers of extra-colonic cancers diagnosed at different stages.

CONCLUSION

HNPCC patients with confirmed MSH2 or MLH1 mutations diagnosed with stages II and III CRC have a good 10-year survival prognoses compared with those from the general population.

[Identification and management of HNPCC syndrome (hereditary non polyposis colon cancer), hereditary predisposition to colorectal and endometrial adenocarcinomas]

BACKGROUND

The HNPCC syndrome (hereditary nonpolyposis colon cancer) is an inherited condition defined by clinical and genealogical information, known as Amsterdam criteria. In about 70% of cases, HNPCC syndrome is caused by germline mutations in MMR genes, leading to microsatellite instability of tumor DNA (MSI phenotype). Patients affected by the disease are at high risk for colorectal and endometrial carcinomas, but also for small intestine, urothelial, ovary, stomach and biliary tract carcinomas. HNPCC syndrome is responsible for 5% of colorectal cancers. Identification and management of this disease are part of a multidisciplinary procedure.

METHODS

Twelve experts have been mandated by the French Health Ministry to analyze and synthesize their consensus position, and the resulting document has been reviewed by an additional group of 4 independent experts.

MAIN RECOMMENDATIONS

The lack of sensitivity of Amsterdam criteria in recognizing patients carrying a MMR germline mutation led to an enlargement of these criteria for the recruitment of possible HNPCC patients, and to a 2-steps strategy, asking first for a tumor characterization according to MSI phenotype, especially in case of early-onset sporadic cases. The identification of germline MMR mutations has no major consequence on the cancer treatments, but influences markedly the long-term follow-up and the management of at-risk relatives. Gene carriers will enter a follow-up program regarding their colorectal and endometrial cancer risks, but other organs being at low lifetime risk, no specific surveillance will be proposed.

Colorectal cancer in African Americans

Colorectal cancer in African Americans has an increased incidence and mortality relative to Whites. The mean age of CRC development in African Americans is younger than that of Whites. There is also evidence for a more proximal colonic distribution of cancers and adenomas in African Americans. African Americans are less likely to have undergone diagnostic testing and screening for colorectal cancer. Special efforts are needed to improve colorectal cancer screening participation rates in African Americans. Clinical gastroenterologists should play an active role in educating the public and primary care physicians about special issues surrounding colorectal cancer in African Americans. Community healthcare groups and gastrointestinal specialists should develop culturally sensitive health education programs for African Americans regarding colorectal cancer. The high incidence and younger age at presentation of colorectal cancer in African Americans warrant initiation of colorectal cancer screening at the age 45 yr rather than 50 yr.

Le syndrome HNPCC (hereditary non polyposis colon cancer) : identification et prise en charge

BACKGROUND

The hereditary non-polyposis colon cancer (HNPCC) syndrome is an inherited condition defined by clinical and genealogical information, known as Amsterdam criteria. In about 70% of cases, HNPCC syndrome is caused by germline mutations in MMR genes, leading to microsatellite instability of tumor DNA (MSI phenotype). Patients affected by the disease are at high risk for colorectal and endometrial carcinomas, but also for other organs tumors. HNPCC syndrome is responsible for 5% of colorectal cancers.

MAJOR ASPECTS

The lack of sensitivity of Amsterdam criteria in recognizing patients carrying a MMR germline mutation led to an enlargement of these criteria for the recruitment of possible HNPCC patients, and to a two-steps strategy, asking first for a tumor characterization according to MSI phenotype, especially in case of early-onset sporadic cases.

FURTHER DEVELOPMENTS

The identification of germline MMR mutations has no major consequence on the cancer treatments, but influences markedly the long-term follow-up and the management of at-risk relatives. Gene carriers will enter a follow-up program regarding their colorectal and endometrial cancer risks; other organs being at low lifetime risk, no specific surveillance will be proposed.

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.

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.

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.

Stromal expression of invasion-promoting, matrix-degrading proteases MMP-1 and -9 and the Ets 1 transcription factor in HNPCC carcinomas and sporadic colorectal cancers

Hereditary nonpolyposis colorectal cancers (HNPCCs) are an important subgroup of colorectal carcinomas. Compared to sporadic variants, they present several particular features, the most important of which are less invasive and metastatic properties linked to a more favorable prognosis. This contrasts to the generally poor differentiation of the epithelial tumor component. Since matrix-degrading proteases secreted by stromal fibroblasts contribute significantly to tumor invasion, we analyzed the stromal expression of 2 matrix metalloproteinases (MMP-1 and -9) and of one of their regulators, the Ets 1 transcription factor, by both immunohistochemistry and in situ hybridization in sporadic colorectal carcinomas and HNPCC tumors. We found that MMP-1 and -9 as well as Ets 1 are upregulated in the fibroblastic stroma during the development from sporadic adenomas to invasive carcinomas. HNPCC tumors exhibited a significantly lower expression of Ets 1, MMP-1 and -9. These findings on the basis of lower matrix-degrading properties of the fibroblastic tumor stroma in HNPCC tumors might help to explain why, in spite of their less differentiated phenotype, HNPCC tumors have a less invasive and metastatic potential compared to sporadic cancers.

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.

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.

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.

Clinical and biologic heterogeneity of hereditary nonpolyposis colorectal cancer

MMR gene mutations and MSI are not found in all clinically diagnosed HNPCC families. We evaluated whether MMR genotyping and tumor MSI analysis could identify distinct clinical subgroups among HNPCC families. Twenty-nine clinical HNPCC families were divided into 3 groups: A, families with hMLH1 or hMSH2 gene mutations; B, MMR gene mutations not present but MSI present in at least 50% of tumors tested; C, mutational and MSI analyses negative. We evaluated tumor spectrum, age at onset, risk of cancer in the follow-up and survival for CRC in the 3 groups. Tumors of the target organs in HNPCC (colon and rectum, endometrium, ovary, small bowel, stomach, renal pelvis and ureter) were more frequent in the first 2 groups than in the latter. Colon cancer was more frequently located in the proximal colon and showed an earlier age at onset in families with MMR gene mutation or with MSI than in families with stable tumors. Comparing the occurrence of tumors in the follow-up, in the first 2 groups patients younger than 50 years had a higher RR, which was particularly marked for CRC (RR = 18.6 for group A vs. group C, RR = 16.7 for group B vs. group C). CRC patients in the first 2 groups had a better clinical prognosis. The results of molecular analysis could distinguish, within clinically defined HNPCC families, different subgroups to which specific programs of surveillance could be addressed.

Microsatellite instability is a favorable prognostic indicator in patients with colorectal cancer receiving chemotherapy

BACKGROUND & AIMS

Adjuvant 5-fluorouracil (5-FU)-based chemotherapy is standard treatment for stage C colorectal cancer (CRC). Approximately 12% of CRCs are characterized by microsatellite instability (MSI), a hallmark of a DNA mismatch repair defect. We investigated the safety of adjuvant 5-FU-based chemotherapy for MSI(+) CRC and compared the prognosis of MSI(+) and MSI(-) CRC patients receiving adjuvant therapy.

METHODS

Previously, a prospective series consisting of 1044 consecutive CRCs has been collected and the MSI status of each sample determined. Patients with stage C cancer who had received adjuvant chemotherapy (n = 95) were followed up for 7-63 months (median, 31 months) after surgery.

RESULTS

No unexpected or serious adverse effects were observed when 5-FU-based chemotherapy was used as adjuvant treatment for MSI(+) CRC. Three- year recurrence-free survival was 90% and 43% in the MSI(+) (n = 11) and MSI(-) (n = 84) groups, respectively (P = 0.020).

CONCLUSIONS

Adjuvant 5-FU-based chemotherapy is feasible for both MSI(+) and MSI(-) CRCs, and patients with MSI(+) CRC who receive adjuvant therapy have an excellent prognosis.

Microsatellite instability in sporadic colorectal cancer is not an independent prognostic factor

Hereditary non-polyposis colorectal cancer (HNPCC) is linked to an inherited defect in the DNA mismatch repair system. DNA from HNPCC tumours shows microsatellite instability (MSI). It has been reported that HNPCC patients have a better prognosis than patients with sporadic colorectal cancer. We examined whether the presence of MSI in a series of unselected colorectal tumours carries prognostic information. In a series of 181 unselected colorectal tumours, 22 tumours (12%) showed MSI. Survival analysis at 5-10 years follow-up showed no statistically significant difference in prognosis between MSI-positive and -negative tumours. Our results suggest that the MSI phenotype as such is not an independent prognostic factor.

Colorectal cancer: molecules and populations

The epidemiology and molecular biology of colorectal cancer are reviewed with a view to understanding their interrelationship. Risk factors for colorectal neoplasia include a positive family history, meat consumption, smoking, and alcohol consumption. Important inverse associations exist with vegetables, nonsteroidal anti-inflammatory drugs (NSAIDs), hormone replacement therapy, and physical activity. There are several molecular pathways to colorectal cancer, especially the APC (adenomatous polyposis coli)-beta-catenin-Tcf (T-cell factor; a transcriptional activator) pathway and the pathway involving abnormalities of DNA mismatch repair. These are important, both in inherited syndromes (familial adenomatous polyposis [FAP] and hereditary nonpolyposis colorectal cancer [HNPCC], respectively) and in sporadic cancers. Other less well defined pathways exist. Expression of key genes in any of these pathways may be lost by inherited or acquired mutation or by hypermethylation. The roles of several of the environmental exposures in the molecular pathways either are established (e.g., inhibition of cyclooxygenase-2 by NSAIDs) or are suggested (e.g., meat and tobacco smoke as sources of specific blood-borne carcinogens; vegetables as a source of folate, antioxidants, and inducers of detoxifying enzymes). The roles of other factors (e.g., physical activity) remain obscure even when the epidemiology is quite consistent. There is also evidence that some metabolic pathways, e.g., those involving folate and heterocyclic amines, may be modified by polymorphisms in relevant genes, e.g., MTHFR (methylenetetrahydrofolate reductase) and NAT1 (N-acetyltransferase 1) and NAT2. There is at least some evidence that the general host metabolic state can provide a milieu that enhances or reduces the likelihood of cancer progression. Understanding the roles of environmental exposures and host susceptibilities in molecular pathways has implications for screening, treatment, surveillance, and prevention.

Survival of patients with hereditary colorectal cancer: comparison of HNPCC and colorectal cancer in FAP patients with sporadic colorectal cancer

Conflicting data exist on the prognosis of hereditary colorectal cancer. HNPCC patients, in particular, are often reported to have a better survival. We examined 2,340 colorectal-cancer patients treated in our Institution: 144 HNPCC patients (Amsterdam Criteria), 161 FAP patients and 2,035 patients with sporadic cancer. Data on hereditary-cancer patients treated between 1980 and 1995 was collected in a registry. The 2,035 sporadic colorectal-cancer patients (controls) included all new cases treated in the Department of Gastrointestinal-Tract Surgery during the same period. Observed survival was estimated using the Kaplan-Meier method. Cumulative survival probability was estimated at 5 years within each group and stratified by various clinical and pathological variables. The age distribution at diagnosis of sporadic patients was significantly higher than that of FAP and HNPCC patients (median 60 years vs. 43 and 49 years; p < 0.0001). In the HNPCC group, 40% had a right cancer location, vs. 14% in the FAP group and 13% in the sporadic-cancer group. In the sporadic group, 51% were early-stage cancers (Dukes A or B) vs. 48.4% and 52.1% in the FAP and HNPCC groups respectively. In the HNPCC, FAP and sporadic-cancer groups, the 5-year cumulative survival rate was 56.9%, 54.4% and 50.6% respectively. Survival analysis by the Cox proportional-hazards method revealed no substantial survival advantage for HNPCC and FAP patients compared with the sporadic group, after adjustment for age, gender, stage and tumor location. The hazard ratio for HNPCC was 1.01 (95% CI 0.72-1.39) and 1.27 (95% CI 0.95-1.7) for FAP patients compared with the sporadic-colorectal-cancer group.

Hereditary non-polyposis colorectal cancer syndrome

Hereditary non-polyposis colorectal cancer (HNPCC) syndrome may account for up to 4% of the total colorectal cancer burden in our community. It is assuming an increasingly important role, both as a clinical management issue and as a model for the application of laboratory and clinical genetic services in cancer detection and prevention. Recent developments in the understanding of the molecular biology of the condition have underpinned recommendations for consideration of genetic testing for DNA mismatch repair gene mutation, recommendations that may have far-reaching implications in terms of the numbers of patients offered genetic testing and for associated costs (both financial and psychological). The aim of this review is to highlight the clinical, pathologic and molecular biologic features of HNPCC that underlie the clinical management of affected index patients and their at-risk family members.

Accumulated clonal genetic alterations in familial and sporadic colorectal carcinomas with widespread instability in microsatellite sequences

A subset of hereditary and sporadic colorectal carcinomas is defined by microsatellite instability (MSI), but the spectra of gene mutations have not been characterized extensively. Thirty-nine hereditary nonpolyposis colorectal cancer syndrome carcinomas (HNPCCa) and 57 sporadic right-sided colonic carcinomas (SRSCCa) were evaluated. Of HNPCCa, 95% (37/39) were MSI-positive as contrasted with 31% (18/57) of SRSCCa (P < 0.000001), but instability tended to be more widespread in SRSCCa (P = 0.08). Absence of nuclear hMSH2 mismatch repair gene product by immunohistochemistry was associated with germline hMSH2 mutation (P = 0.0007). The prevalence of K-ras proto-oncogene mutations was similar in HNPCCa and SRSCCa (30% (11/37) and 30% (16/54)), but no HNPCCa from patients with germline hMSH2 mutation had codon 13 mutation (P = 0.02), and two other HNPCCa had multiple K-ras mutations attributable to subclones. 18q allelic deletion and p53 gene product overexpression were inversely related to MSI (P = 0.0004 and P = 0.0001, respectively). Frameshift mutation of the transforming growth factor beta type II receptor gene was frequent in all MSI-positive cancers (85%, 46/54), but mutation of the E2F-4 transcription factor gene was more common in HNPCCa of patients with germline hMSH2 mutation than in those with germline bMLH1 mutation (100% (8/8) versus 40% (2/5), P = 0.04), and mutation of the Bax proapoptotic gene was more frequent in HNPCCa than in MSI-positive SRSCCa (55% (17/31) versus 13% (2/15), P = 0.01). The most common combination of mutations occurred in only 23% (8/35) of evaluable MSI-positive cancers. Our findings suggest that the accumulation of specific genetic alterations in MSI-positive colorectal cancers is markedly heterogeneous, because the occurrence of some mutations (eg, ras, E2F-4, and Bax genes), but not others (eg, transforming growth factor beta type II receptor gene), depends on the underlying basis of the mismatch repair deficiency. This genetic heterogeneity may contribute to the heterogeneous clinical and pathological features of MSI-positive cancers.