Family and personal history in colorectal cancer patients: what are we missing?

OBJECTIVE: Family and personal history of colorectal cancer and associated tumours are crucial in identifying families with hereditary nonpolyposis colorectal cancer (HNPCC). The aim of this study was to determine the adequacy of these aspects of history-taking in the management of colorectal cancer patients. PATIENTS AND METHODS: Colorectal cancer patients attending outpatient follow-up were interviewed to obtain a detailed family and personal history of cancers. The medical notes were then reviewed to identify whether these had been documented previously. RESULTS: One hundred and one patients took part. In seven, no family history had been recorded; none of these actually had a significant pedigree. In 88, the family history was not significant, a finding correctly documented in the records. Three had a high-risk family history and another three had a personal history of other possible HNPCC-related cancers. In each of these patients, the relevant findings had been documented, but no further action had been taken. CONCLUSIONS: Family history was taken in the majority of patients, but in the only three with a pedigree indicative of HNPCC, its significance was not appreciated. The potential relevance of multiple HNPCC-related cancers in the same individual was also overlooked. Improved education and referral pathways are needed to ensure that families with HNPCC have access to appropriate surveillance and genetic testing.

Molecular genetics improves the management of hereditary non-polyposis colorectal cancer.

BACKGROUND: The syndrome of hereditary non-polyposis colorectal cancer (HNPCC) can be diagnosed fairly accurately using clinical criteria and a family history. Identifying HNPCC helps to prevent large-bowel cancer, or allows cancer to be treated at an early stage. Once the syndrome has been diagnosed a family member's risk can be judged approximately from a family tree, or it can now be predicted accurately if the causative mutation is known. OBJECTIVE: This study involved attempts to improve the management of a family with HNPCC over a period of 10 years. Clinical diagnostic criteria, colonoscopic surveillance, surgical treatment, genetic counselling, molecular genetic research, and finally predictive genetic testing were applied as they evolved during this time. SUBJECTS AND METHODS: A rural general practitioner first noted inherited large-bowel cancer in the family and began screening subjects as they presented, using rigid sigmoidoscopy at the local hospital. At the time that the disorder was recognised as being HNPCC (1987), screening by means of colonoscopy at our university hospital was aimed primarily at first-degree relatives of affected individuals. After realising how many were at risk, screening was brought closer to the family. A team of clinicians and researchers visited the local hospital to identify and counsel those at risk and to perform screening colonoscopy. Family members were recruited for research to find the gene and its mutation that causes the disease, to develop an accurate predictive test and to reduce the number of subjects undergoing surveillance colonoscopies. RESULTS: There are approximately 500 individuals in this family. In the 10 years of this study the number of subjects who have been counselled for increased genetic risk or who have requested colonoscopic surveillance for HNPCC in this kindred has increased from 20 to 140. After the causative mutation was found in the hMLH1 gene on chromosome 3, a test for it has reduced the number of subjects who need screening colonoscopy by over 70%. A protocol has been devised to inform family members, to acquire material for research in order to provide genetic counselling for (pre-test and post-test) risk, and to test for the mutation. Eventually, identifying those with the mutation should focus surveillance accurately. CONCLUSIONS: The benefits of restricting screening to subjects with the mutation that causes colorectal cancer and of performing operations to prevent cancer are hard to measure accurately. However, it is likely that at least half the family members will be able to avoid colonoscopic screening, some deaths from cancer should be prevented, and the cost of preventing and treating cancer in the family should fall substantially.

In a resource-poor country, mutation identification has the potential to reduce the cost of family management for hereditary nonpolyposis colorectal cancer.

PURPOSE: Colonoscopic surveillance of family members at risk of hereditary nonpolyposis colorectal cancer is difficult in a resource-poor country because of its expense. For family members who live in remote areas, poor communication and limited access to sophisticated medical care make surveillance even more difficult. The identification of the mutation causing the disease will simplify surveillance. Our aim was to assess the impact of mutation analysis on the management of a South African family with more than 150 members at risk for hereditary nonpolyposis colorectal cancer. METHODS: We studied a family that met the Amsterdam criteria for hereditary nonpolyposis colorectal cancer. Colorectal cancer affected 27 members in three generations (evidence from histology in 12, barium enema in 1, and family statements in 14 family members). Leukocyte DNA from family members was tested for linkage to candidate loci for colorectal cancer, and DNA from formalin-fixed cancers from six family members was studied for microsatellite instability. DNA from all available family members was then screened for mutations in the hMLH1 gene. The number of individuals at 50 percent risk was calculated by family pedigree and compared with the number who have the mutation. RESULTS: A disease-causing mutation in exon 13 of hMLH1 segregated with the disorder in members of this kindred. Test results of 100 chromosomes from population-matched controls were negative. Sixty family members between the ages of 16 and 50 years are at 50 percent risk for colon cancer by pedigree analysis, but of these, only 26 (43 percent) have the mutation. CONCLUSION: A mutation in the DNA repair gene hMLH1 was found in family members with hereditary nonpolyposis colorectal cancer and in some unaffected relatives previously at 50 percent risk, but not in unrelated subjects. The blood test for the mutation will simplify management, counseling, and surveillance and help to establish prophylactic colectomy.

Use of SSCP analysis to identify germline mutations in HNPCC families fulfilling the Amsterdam criteria.

Hereditary non-polyposis colorectal cancer (HNPCC) is a clinical syndrome characterised by an inherited predisposition to early onset colorectal and uterine cancers and an increased incidence of other cancers. It is caused by germline defects in the human mismatch repair genes. Defects in two of the known mismatch repair genes (namely hMSH2 and hMLH1) account for over 90% of mutations found in HNPCC families. In this study we have identified 14 families that fulfilled the clinical criteria for HNPCC and screened the hMSH2 and hMLH1 genes for germline mutations using single-strand conformational polymorphism (SSCP) analysis and DNA sequencing. Seven mutations were identified. Of these, there were five frameshifts, one missense mutation and a further novel mutation that involved separate transition and transversion changes in successive amino acid residues. Three of the mutations were in hMSH2 and four in hMLH1. The identification of germ-line mutations in an HNPCC family enables targeted surveillance and the possibility of early curative intervention. SSCP is a simple and effective method for identifying most mutations in the human mismatch repair genes using DNA from fresh, frozen or archival material.

Genetic testing is important in families with a history suggestive of hereditary non-polyposis colorectal cancer even if the Amsterdam criteria are not fulfilled.

BACKGROUND: Clinical screening is still the first-line approach to identification of families with hereditary non-polyposis colorectal cancer (HNPCC). The need for uniformity of diagnosis of the syndrome, particularly in multicentre studies, led to the establishment of a set of minimum diagnostic criteria, the 'Amsterdam criteria'. It is now known that HNPCC is caused by germline defects in the human mismatch repair genes and DNA predictive testing is possible. Defects in two of the known mismatch repair genes, namely hMSH2 and hMLH1, account for over 90 per cent of mutations found in HNPCC families. METHODS: Ten families were identified with pedigrees suggestive of HNPCC (that is with a possible dominant inheritance of HNPCC), but in which the Amsterdam criteria were not fulfilled. Using the technique of single-strand conformational polymorphism analysis, samples were screened from an affected member of each of these ten kindreds for germline mutations in the genes hMSH2 and hMLH1. RESULTS: Mutations were identified in six families. Of these, there were three missense, one nonsense, one frameshift and one putative splice-site mutation. Three of the mutations were in hMSH2 and three in hMLH1. CONCLUSION: This study demonstrates that all families with a pedigree suggestive of HNPCC should be referred to a geneticist even if the Amsterdam criteria are not fulfilled. A knowledge of the gene carrier status enables targeted surveillance and the possibility of early surgical intervention that could be curative.

Clinical features and molecular analysis of a family with multiple colon tumours and reduced plasminogen activator activity.

A family is reported in which a pair of brothers has developed recurrent venous thromboses, which have been shown in one brother (the proband) to result from a reduced level of tissue plasminogen activator (t-PA) activity. Both brothers have also developed multiple synchronous and metachronous colorectal adenomas. Other pedigree members have developed colon cancers, but not multiple colonic tumours. We have shown that HNPCC and FAP/AAPC are unlikely causes of the family's phenotypes. Previous studies have found low levels of t-PA in sporadic colon tumours. In this family, mutations in the t-PA gene, at a linked locus, or at a locus controlling t-PA activity/release may modify the colon tumour phenotype to cause multiple lesions.

Germline HNPCC gene variants have little influence on the risk for sporadic colorectal cancer.

Hereditary non-polyposis colorectal cancer (HNPCC) is a syndrome of inherited bowel and other cancers that has been said to account for up to 15% of all colorectal carcinomas (CRCs). HNPCC can now be diagnosed at the molecular level by detecting germline mutations in genes involved in mismatch repair. A current problem is to determine the prevalence of HNPCC mutations in colon cancer patients with limited or no family history, especially in cases of early onset. We have identified 50 cases of non-polyposis colorectal cancer without a family history of CRC or any other HNPCC cancer, who presented under the age of 45 years. Germline HNPCC variants (at the hMSH2 or hMLH1 loci) were detected in a small minority of cases (6%). The variants that we have found may be new or low penetrance mutations, or even polymorphisms. It remains possible that some of our sample have an inherited predisposition to CRC that is not caused by HNPCC mutations or by known polyposis syndromes. Our data suggest that most HNPCC mutations occur in families and have high or moderate penetrance. New or low penetrance HNPCC mutations probably do not contribute significantly to the risk of colorectal cancer in the general population and probably account for much fewer than 15% of all CRCs. Our results question whether mass population genetic screening programmes are worthwhile for diseases such as HNPCC using current technology.

Screening results in a family cancer clinic: five years experience.

We present our experience so far of screening individuals referred to the Cancer family clinic at St. Mark's Hospital from 1986, with the results of the follow-up of these individuals. 651 individuals from 436 families were offered colonoscopic surveillance at five-yearly intervals. The median age at which the examination was performed was 41 years. Families were subdivided according to family history; 15.8% conformed to the Amsterdam criteria for hereditary nonpolyposis colorectal cancer (HNPCC). The pathological findings were correlated with the type of pedigree; abnormalities were more often found in males than females (30% of colonoscopies in males revealed adenomas, and 17% in females), and adenoma prevalence increased with age. Adenoma prevalence (27% v.s. 21% at all ages, and 38% v.s. 25% in individuals over the age of 35y.), multiple adenomas and the proportion of proximally sited adenomas were all higher in HNPCC families; however, dysplasia and villous or large adenomas were not more common in individuals from HNPCC families. Four of the 7 carcinoma detected were in HNPCC families (3% v.s. 0.6%).

Congenital hypertrophy of retinal pigment epithelium in patients with colonic polyps associated with cancer family syndrome.

Congenital hypertrophy of retinal pigment epithelium (CHRPE) has been shown to be a frequent extracolonic manifestation of adenomatous polyposis coli (APC). The presence of CHRPE in patients with adenomatous polyps from families with cancer family syndrome suggests possible involvement of the APC gene locus in syndromes associated with less florid polyp formation than seen in APC. It also emphasises that caution must be exercised in using the presence of CHRPE clinically as a marker for APC in isolated at-risk individuals.

Risk of cancer death in first-degree relatives of patients with hereditary non-polyposis cancer syndrome (Lynch type II): a study of 130 kindreds in the United Kingdom.

To estimate the relative risks of cancer in first-degree relatives of index patients, 130 pedigrees of dominantly inherited Lynch type II cancer family syndrome have been analysed. The risk of death from all causes was significantly increased in women over 45 years of age and the overall liability to cancer in women was greater than for men. A sevenfold increase in risk of colon cancer was found in both sexes. In female relatives the risk of breast cancer was increased fivefold and lifetime risk of breast cancer was 1 in 3.7. A screening programme based on estimated risks could be offered to first-degree relatives of index patients with Lynch type II cancer family syndrome.

Screening and genetic counselling for relatives of patients with colorectal cancer in a family cancer clinic.

OBJECTIVE: To introduce and monitor a screening programme for first degree relatives of patients with colorectal cancer based on their calculated lifetime risk. DESIGN: Lifetime risks were calculated for first degree relatives of patients with colorectal cancer and used to offer screening based on estimated risk. SETTING: A family cancer clinic was set up as part of the North East Thames Regional Genetic Service for relatives of patients who had developed colorectal cancer before the age of 45 and members of families in which multiple cancer had occurred. PATIENTS: Self referrals as well as patients referred by general and hospital practitioners. INTERVENTION: Relatives with a lifetime risk of 1 in 10 or greater (high risk group) were offered screening five yearly by colonoscopy, and those whose risk was between 1 in 10 and 1 in 17 were offered yearly screening for faecal occult blood. Women with family histories compatible with Lynch type II cancer family syndrome were offered screening for breast and pelvic tumours. RESULTS: In four years 715 patients were seen. Acceptance of screening was 90% (644 patients). Of 151 patients screened for faecal occult blood, two were found to have polyps. This screening test was unsatisfactory for the high risk group, having a negative predictive value of 78% in 59 patients tested. Regular screening by colonoscopy was offered to 382 high risk patients; 62 patients with polyps and five with colonic cancer were found. One hundred and ten pedigrees were identified with the Lynch type II cancer family syndrome, and four of 35 women screened were found to have breast cancer. Of 14 relatives aged over 65 with a 1 in 2 risk of site specific colonic cancer or Lynch type II cancer family syndrome, seven were found to have polyps, one of whom had carcinoma in situ. CONCLUSIONS: Family history can be used to identify those at risk of colonic cancer and to target appropriate screening. Colonoscopy detected a high number of premalignant colonic polyps, but faecal occult blood testing was unsatisfactory for those at high risk of colorectal cancer.