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

The genetic basis of Lynch syndrome and its implications for clinical practice and risk management

Lynch syndrome is the most common cause of hereditary colon cancer, and accounts for as much as 3% of all colon and endometrial cancers. The identification and management of individuals with Lynch syndrome have evolved over the past 20 years, yet the syndrome remains vastly underdiagnosed. It is important for clinicians to recognize individuals and families who are at risk in order to be able to manage them appropriately and reduce their morbidity and mortality from this condition. This review will touch on the history of Lynch syndrome, the current knowledge of genotype–phenotype correlations, the cancers associated with Lynch syndrome, and management of individuals who are gene carriers.

Impact of colonoscopic screening in male and female Lynch syndrome carriers with an MSH2 mutation

The lifetime risk of developing colorectal cancer (CRC) in Lynch syndrome (LS) carriers is very high. To determine the impact of colonoscopic screening in 54 male and 98 female MSH2 mutation carriers, outcomes were compared with 94 males and 76 females who were not screened. CRC incidence and survival in the screened group were compared to that expected, derived from the non-screened group. To correct for survivor bias, controls were matched for age at entry into screening and also for gender. In males, median age to CRC was 58 years, whereas expected was 47 years (p = 0.000), and median survival was 66 years vs 62 years (p = 0.034). In screened females, median age to CRC was 79 years compared to 57 years in the non-screened group (p = 0.000), and median survival was 80 years compared with expected of 63 years (p = 0.001). Twenty percent of males and 7% of females developed an interval CRC within 2 years of previous colonoscopy. Although colonoscopic screening was associated with decreased CRC risk and better survival, CRCs continued to occur. CRC development may be further reduced by decreasing the screening interval to 1 year and improving quality of colonoscopy.

Lynch syndrome: barriers to and facilitators of screening and disease management

Background

Lynch syndrome is a hereditary cancer with confirmed carriers at high risk for colorectal (CRC) and extracolonic cancers. The purpose of the current study was to develop a greater understanding of the factors influencing decisions about disease management post-genetic testing.

Methods

The study used a grounded theory approach to data collection and analysis as part of a multiphase project examining the psychosocial and behavioral impact of predictive DNA testing for Lynch syndrome. Individual and small group interviews were conducted with individuals from 10 families with the MSH2 intron 5 splice site mutation or exon 8 deletion. The data from confirmed carriers (n = 23) were subjected to re-analysis to identify key barriers to and/or facilitators of screening and disease management.

Results

Thematic analysis identified personal, health care provider and health care system factors as dominant barriers to and/or facilitators of managing Lynch syndrome. Person-centered factors reflect risk perceptions and decision-making, and enduring screening/disease management. The perceived knowledge and clinical management skills of health care providers also influenced participation in recommended protocols. The health care system barriers/facilitators are defined in terms of continuity of care and coordination of services among providers.

Conclusions

Individuals with Lynch syndrome often encounter multiple barriers to and facilitators of disease management that go beyond the individual to the provider and health care system levels. The current organization and implementation of health care services are inadequate. A coordinated system of local services capable of providing integrated, efficient health care and follow-up, populated by providers with knowledge of hereditary cancer, is necessary to maintain optimal health.

Endoscopic surveillance for hereditary non-polyposis colorectal cancer (HNPCC) family members in a Southern Italian region

BACKGROUND

Surveillance in hereditary non-polyposis colorectal cancer (HNPCC) family members recommends baseline colonoscopy starting at age 20 and then surveillance colonoscopy every 1-2 years.

AIMS

To verify adherence to the guidelines for HNPCC family members enrolled in endoscopic surveillance.

METHODS

Data regarding 11 HNPCC families was retrieved from our database. Excluding 11 probands, 106 family members were evaluated and 40 underwent surveillance.

RESULTS

At baseline colonoscopy, 7 colorectal cancers (CRC), 14 polyps (PO) [1 inflammatory, 2 hyperplastic, 10 adenomas with low grade dysplasia (LGD-AD) and 1 adenoma with high-grade dysplasia (HGD-AD)] were diagnosed in sixteen individuals. Twenty-eight HNPCC family members underwent endoscopic surveillance, with a total of 94 surveillance colonoscopies. Of these, 45 were positive (4 CRC, 3 inflammatory PO, 34 hyperplastic PO, 21 LGD-AD and 5 HGD-AD). Mean time between two consecutive surveillance colonoscopies was 24.6 months (range 4-168). Median time to first positive surveillance colonoscopy was 84 months for HNPCC family members with negative baseline colonoscopy, and 60 months for those with positive baseline colonoscopy (p=0.21).

CONCLUSIONS

Our data suggests that surveillance colonoscopy every 2 years is adequate to diagnose advanced lesions in HNPCC family members, and improves their compliance with surveillance.

Current hypotheses on how microsatellite instability leads to enhanced survival of Lynch Syndrome patients

High levels of microsatellite instability (MSI-high) are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS) colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI-high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.

Improving the quality of colorectal cancer screening: assessment of familial risk

BACKGROUND

Accuracy of familial risk assessment by endoscopists in determining colonoscopic screening and surveillance intervals is unknown.

AIMS

To investigate follow-up recommended by endoscopists for individuals at average or increased familial risk, following colonoscopies that were normal or yielded hyperplastic polyps only.

METHODS

Colonoscopy registry data was analyzed on 5,982 patients who had colonoscopy between 2004 and 2006. Patient information was linked with colonoscopy procedure information and pathology results. Patients with a personal or family history of colorectal cancer (CRC) or polyps, inflammatory bowel disease, or who had diagnostic, incomplete or suboptimally prepped examinations were excluded. The final analysis, which included 2,414 patients, investigated concordance of risk assessment between patient and endoscopist, and resulting endoscopist follow-up recommendations.

RESULTS

Following normal colonoscopy, 76% of average risk individuals were told to follow-up in 10 years, but if a hyperplastic polyp was found, less than 10 years was suggested for 76%. Many patients reporting a known familial cancer syndrome or a very strong family history did not have that history indicated on the endoscopist's procedure form, and recommended follow-up intervals were beyond guideline recommendations for 60.4% of the very high-risk group.

CONCLUSIONS

Endoscopists may sometimes be unaware of the presence of familial risk factors, even for individuals at very high familial risk. Greater consistency and accuracy in familial risk assessments could significantly increase the efficacy of screening in preventing colorectal cancer.

Surveillance colonoscopy improves survival in a cohort of subjects with a single mismatch repair gene mutation

OBJECTIVE

Previous studies have shown a benefit for surveillance colonoscopy in heterogeneous groups of subjects with suspected or proven hereditary nonpolyposis colon cancer. The aim of this study was to investigate whether surveillance colonoscopy improves the survival in subjects who all carry a single mismatch repair gene defect.

METHOD

This is a prospective cohort study of 178 subjects who carry a mutation of the MLH1 gene in exon 13 (C1528T). They were offered surveillance colonoscopy between 1988 and 2006, and were followed up until September 2007.

RESULTS

One hundred and twenty-nine subjects underwent surveillance colonoscopy, and 49 declined. After a median follow up of 5 years, colorectal cancer was diagnosed in 14/129 (11%) subjects in the surveillance group and 13/49 (27%) in the nonsurveillance group (P = 0.019). Cancers in the surveillance group were at an earlier stage than in the nonsurveillance group (P = 0.032). Death from colorectal cancer occurred in three of 129 (2%) subjects in the surveillance group, and six of 49 (12%) in the nonsurveillance group (P = 0.021). The Kaplan-Meyer estimates for median survival from birth were 78 years in the surveillance group, and 55 years in the nonsurveillance group (P = 0.024). The Kaplan-Meyer estimates for median colorectal cancer-free survival from birth were 73 years in the surveillance group and 47 years in the nonsurveillance group (P = 0.0089).

CONCLUSION

Surveillance colonoscopy was associated with improved overall and colorectal cancer-related survival in subjects carrying a single mismatch repair gene mutation.

Adenoma-infiltrating lymphocytes (AILs) are a potential marker of hereditary nonpolyposis colorectal cancer

Patients with hereditary nonpolyposis colorectal cancer syndrome (HNPCC) develop microsatellite-unstable colorectal cancers that tend to be more proximally located and are histologically more likely to show high numbers of tumor-infiltrating lymphocytes, a lack of dirty necrosis, mucinous or poor differentiation, and a Crohn-like host immune response, when compared with microsatellite-stable cancers. However, histologic features that are characteristic of and can perhaps distinguish colorectal adenomas in HNPCC patients from those occurring in the general population have not been previously reported. We compared 16 adenomas endoscopically removed from patients with genetically proven HNPCC to 32 control adenomas, group-matched for patient age and sex, along with endoscopic size, shape, anatomic location, and presence of high-grade dysplasia. Adenomas from HNPCC patients were more likely to contain high numbers of adenoma-infiltrating lymphocytes (AILs) with 12 of 16 (75%) adenomas having >or=5 AILs per high-power field (HPF) as opposed to 4 of 32 (12%) adenomas in the control group (P=0.00003). HNPCC adenomas were also less likely to contain increased numbers of apoptotic bodies: 7 of 16 (44%) contained >or=5 apoptoses per HPF, compared with 27 of 36 (84%) control adenomas (P=0.006). The presence of necrosis or serrated architecture, percent villous component, and numbers of mitotic figures per HPF did not differ significantly between the 2 groups. Therefore, increased numbers of AILs and decreased numbers of apoptoses in colorectal adenomas are simple and inexpensive markers that raise the possibility of HNPCC.

Development of colorectal tumors in colonoscopic surveillance in Lynch syndrome

BACKGROUND & AIMS

Mutation carriers in Lynch syndrome families have a high risk for developing colorectal cancer during their lifetime. This study was designed to assess the cumulative risk for the development of colorectal adenoma or carcinoma in prospective colonoscopic surveillance.

METHODS

Data from the Finnish Hereditary Colorectal Cancer Registry electronic database on 420 Lynch syndrome mutation carriers without previous colorectal tumors were reviewed. Between March 1982 and May 2005 the mutation carriers underwent a total of 1252 colonoscopies. The total follow-up time was 3150 years (mean, 6.7 y/patient).

RESULTS

The cumulative risk of adenoma by age 60 was estimated as 68% (95% confidence interval [CI], 50%-80%) in men and 48% (95% CI, 29%-62%) in women. The estimated cumulative risk up to age 60 years for the development of cancer found as a result of surveillance at an interval of 2-3 years was 35% (95% CI, 16%-49%) in men and 22% (95% CI, 7%-34%) in women. Half of the adenomas were located proximal to the splenic flexure. Extracolonic cancer was diagnosed in 73 patients (18%).

CONCLUSIONS

Adenoma would appear to be the most important lesion preceding cancer formation in Lynch syndrome and removal of adenomas decreases the risk for colorectal cancer (CRC). The Finnish surveillance protocol of colonoscopies at 2- to 3-year intervals facilitates patient adherence but includes an essential risk for CRC up to 60 years of age, but without CRC-related mortality when the surveillance instructions are followed.

Hereditary non-polyposis colorectal cancer: The rise and fall of a confusing term

The term Hereditary Non-Polyposis Colorectal Cancer (HNPCC) is a poor descriptor of the syndrome described by Lynch. Over the last decade, the term has been applied to heterogeneous groups of families meeting limited clinical criteria, for example the Amsterdam criteria. It is now apparent that not all Amsterdam criteria-positive families have the Lynch syndrome. The term HNPCC has also been applied to clinical scenarios in which CRCs with DNA microsatellite instability are diagnosed but in which there is no vertical transmission of an altered DNA mismatch repair (MMR) gene. A term that has multiple, mutually incompatible meanings is highly problematic, particularly when it may influence the management of an individual family. The Lynch syndrome is best understood as a hereditary predisposition to malignancy that is explained by a germline mutation in a DNA MMR gene. The diagnosis does not depend in an absolute sense on any particular family pedigree structure or age of onset of malignancy. Families with a strong family history of colorectal cancer that do not have Lynch syndrome have been grouped as ‘Familial Colorectal Cancer Type-X’. The first step in characterizing these cancer families is to distinguish them from Lynch syndrome. The term HNPCC no longer serves any useful purpose and should be phased out.