Hereditary nonpolyposis colorectal cancer

Descriptive Epidemiology of Hereditary Non-Polyposis Colorectal Cancer

Hereditary non-polyposis colorectal cancer (HNPCC or Lynch syndrome) is characterized by early occurrence of colorectal malignancies, localization of tumors in the proximal colon, frequency of multiple primaries (both synchronous and metachronous) and an autosomal dominant type of genetic transmission. HNPCC has been reported in many races and populations, including Japanese, Philipinos and American Indians. The frequency of the disease ranges between 1 and 5% of all colorectal malignancies. In northern Italy, the frequency of HNPCC has been estimated in the order of 2.8-3.0% of all registered cancers of the large bowel, while lower estimates have been recorded in southern regions. The identification of HNPCC remains difficult, mainly because the full-blown syndrome does not become manifest until several family members are affected with cancer. The recent identification of at least four genes responsible, when mutated, for the clinical spectrum of Lynch syndrome should be of considerable help in recognizing this type of tumors in the general population.

Soy food and isoflavone intake and colorectal cancer risk: the Fukuoka Colorectal Cancer Study

OBJECTIVE

It has been suggested that soy food and isoflavone intake may be protective against the risk of colorectal cancer. However, epidemiologic evidence remains sparse and inconsistent. We addressed this issue in the Fukuoka Colorectal Cancer Study.

MATERIAL AND METHODS

The study subjects were the 816 incident cases of histologically confirmed colorectal cancer and 815 community controls. Intakes of soy foods and isoflavones were assessed by in-person interview using a computer-assisted dietary method. Logistic regression analysis was applied to estimate odds ratio (OR) and 95% confidence interval (CI) of colorectal cancer with adjustment for dietary intakes of calcium and n-3 polyunsaturated fatty acids as well as for body mass index, physical activity, alcohol use, and other lifestyle factors.

RESULTS

Energy-adjusted intakes of soy foods (dry weight) and isoflavones were inversely associated with colorectal cancer risk in men and postmenopausal women, but not in premenopausal women. The multivariate-adjusted OR for the highest versus lowest quintile was 0.65 (95% CI 0.41-1.03, p for trend = 0.03) for soy foods and 0.68 (95% CI 0.42-1.10, p for trend = 0.051) for isoflavones in men. The corresponding values for postmenopausal women were 0.60 (95% CI 0.29-1.25, p for trend = 0.053) and 0.68 (95% CI 0.33-1.40, p for trend = 0.049). The site-specific analysis showed inverse associations of soy foods (p for trend = 0.007) and isoflavones (p for trend = 0.02) with rectal cancer in men.

CONCLUSION

The findings add to epidemiologic evidence for protective effects of soy foods and isoflavones in colorectal carcinogenesis.

Colonoscopy for screening and follow up of patients with a family history of colorectal cancer

OBJECTIVE

To determine the minimum family history of colorectal cancer (CRC), which justifies colonoscopy and to establish whether further colonic assessment is necessary after a negative screening colonoscopy.

METHOD

A retrospective review of every colonoscopy undertaken for family screening at the Royal Berkshire and Battle Hospitals, Reading between October 1996 and July 2004.

RESULTS

Four hundred and thirty-two patients (261 women) with an average age of 48 years (range 14-84) were screened. Three cancers in patients over the age of 60 years and 49 adenomas were found in 37 patients. Twenty three of 281 (8%) patients with a 'low-risk' family history (one in 12 or less lifetime risk of developing CRC) had either a cancer or an adenoma. Eighteen of 151 (12%) patients with a 'high-risk' family history (one in 10 or greater) had a similar positive colonoscopy. Thirteen of 15 patients who had an adenoma aged under 45 years had a high-risk family history. Seventy-three patients subsequently underwent two or more follow-up colonoscopies. There were 22 adenomatous polyps found in 12 patients (16%) at the first screening, nine adenomas in seven patients in the second colonoscopy and four adenomas found in four patients in all subsequent colonoscopies.

CONCLUSION

Patients with a low-risk family history have a similar adenoma pick-up to that of the general population. These patients need not be screened below the age of 50 unless symptomatic. Follow up of low-risk family history (FH) patients with a negative screening colonoscopy is unlikely to be beneficial.

Compliance and Satisfaction with Long-Term Surveillance in Finnish HNPCC Families

OBJECTIVE

Nation-wide preventative colonoscopic surveillance for mutation carriers in HNPCC families has been organized since the early 1980 by the Finnish HNPCC registry. After characterization of MMR genes, a predisposing mutation has been verified in 111 HNPCC families and over 1500 family members at risk have been tested. The aim of this study was to evaluate the compliance and satisfaction of mutation carriers during life-long colonoscopic surveillance.

MATERIALS AND METHODS

Hospital records of long-term surveillance were obtained for all mutation carriers (n=664). A questionnaire assessing overall experience, willingness to continue the surveillance, painfulness (a three-rank scale), possible interruption of endoscopy and the need for pain relief medication during colonoscopy, was sent to all living mutation carriers (n=587). The questionnaire was returned by 441 persons (75%) of whom 415 persons under colonoscopic surveillance were included in the study and 26 young mutation carriers excluded as they were still pending their first endoscopy.

RESULTS

Out of 664 mutation carriers, surveillance had been interrupted in 8 cases (1.2%). Colonoscopies were described as painful by 151 (36%), uncomfortable by 161 (39%) and easy by 103 (25%) patients. Endoscopy was more often rated as painful by females (1.36, SD 0.71) than by males (0.86, SD 0.75), P<0.001. Medication for pain during colonoscopies was administered more often to females (32%) than males (15%), P<0.001. Colonoscopy had to be discontinued because of pain at least once in 10% of the patients.

CONCLUSION

Patient compliance under life-long surveillance was excellent, but painfulness, especially in females, must be seen as a risk for compliance and the quality of endoscopies.

Low mutation rate of hMSH2 and hMLH1 in Taiwanese hereditary non-polyposis colorectal cancer

Hereditary non-polyposis colorectal cancer (HNPCC), the most common type of hereditary colorectal cancer, is thought to be a simple Mendelian disease involving DNA mismatch repair genes. The majority of mutations associated with HNPCC occur in the hMSH2 and hMLH1 genes. The reported incidence of mismatch repair gene mutations in HNPCC kindreds varies considerably (from 22 to 86%), and most mutations are unique. This study aimed to determine the genetic basis of Taiwanese HNPCC kindreds, focusing on the two major genes involved in this disease. A total of 15 Taiwanese HNPCC kindreds meeting the Amsterdam criteria, including 72 affected individuals among a total of 266 individuals, were analyzed using both RNA- and DNA-based methods. The mutation rate of hMSH2 and hMLH1 in these 15 kindreds was 0% and 20%, respectively, which is lower than that reported in other countries. Two novel mutations were discovered in hMLH1: one was an allelic loss of a 5.2-kb genomic fragment causing exon 16 deletion; and the other was a two-nucleotide deletion that resulted in a frameshift mutation of exon 3. We also identified one hMLH1 exon 4 mutation (a C to T transition in codon 117), which had been reported previously in western countries. This is the first genetic study of HNPCC from Taiwan.

Colorectal cancer screening and familial risk: a survey of internal medicine residents' knowledge and practice patterns

OBJECTIVE

Risk stratification is essential to the appropriate use of colorectal cancer screening recommendations. The principal objective of this study was to assess the knowledge and screening behavior of internal medicine (IM) residents regarding familial colorectal cancer.

METHODS

We conducted a survey of IM residents in their second and third year of postgraduate training from two university-based programs (n = 127). The survey instrument assessed physician knowledge of screening recommendations and current practices for individuals with a family history of colorectal cancer, adenomatous polyps, familial adenomatous polyposis, and hereditary nonpolyposis colorectal cancer. The instrument also elicited data regarding familial risk assessment, documentation, and notification of at-risk family members.

RESULTS

Eighty-one IM eligible residents (81%) completed the survey. Most respondents identified a family history of colorectal cancer as an important factor in assessing colorectal cancer risk and appropriately implemented relevant screening recommendations. However, for patients with a family history of adenomatous polyps diagnosed before age 60 yr, knowledge and adherence to recommendations advocating screening at age 40 was relatively poor. More importantly, for patients with familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer, respondents lacked the necessary risk assessment skills and knowledge to appropriately implement current recommendations. There were no consistent differences in knowledge or screening behavior when stratified on the basis of program site or postgraduate year status.

CONCLUSION

Many IM residents are deficient in their knowledge, risk assessment skills, and screening practices for patients at familial risk of colorectal cancer. Effective educational strategies that promote awareness regarding familial risk, risk assessment skills, and appropriate use of relevant screening guidelines are needed.

Family history and colorectal cancer screening: a survey of physician knowledge and practice patterns

OBJECTIVES

Risk stratification is essential to effective implementation of colorectal cancer (CRC) screening strategies. The objectives of this study were to assess and compare the current knowledge and practice patterns of gastroenterologists and primary care physicians regarding familial risk of CRC.

METHODS

We conducted a survey of regional gastroenterologists and a sample of university- and community-based primary care physicians. The survey instrument assessed physician knowledge of screening recommendations and current practices for individuals with family histories of CRC, adenomatous polyps (APs), familial adenomatous polyposis (FAP), and hereditary nonpolyposis cancer (HNPCC). The instrument also elicited data about familial risk assessment, documentation, and notification of at-risk family members.

RESULTS

Thirty-five gastroenterologists (65%) and 58 primary care physicians (92%) completed the survey. Most gastroenterologists and primary care physicians (85% vs 72%) chose age 40 as the appropriate age to begin screening for a family history of CRC, but relatively few (37% vs 36%) recommended screening at age 40 for a family history of APs. Gastroenterologists were significantly more likely to recommend screening for FAP at puberty (80% vs 27%, p < 0.001) and for HNPCC at age 25 (73% vs 50%, p = 0.04). Colonoscopy was the preferred screening strategy by both groups for family histories of CRC (97%), HNPCC (97%), and APs (77%); primary care physicians also preferred colonoscopy for family histories of CRC (72%) and HNPCC (76%) but flexible sigmoidoscopy plus fecal occult blood testing for a family history of APs (38%). Gastroenterologists were more likely to recommend genetic testing for persons at risk of FAP (91% vs 71%, p = 0.03) and HNPCC (72% vs 57%, p = 0.18), routinely inquire about a family history of CRC or APs (93% vs 63%, p < 0.001), and recommend notification of at-risk first-degree relatives with family histories of CRC (94% vs 55%, p < 0.001) or AP (53% v.s 6%, p < 0.001).

CONCLUSION

Although gastroenterologists are more likely than primary care physicians to elicit a family history of colorectal neoplasia and implement appropriate screening strategies, overall compliance with recommended guidelines and notification of at-risk relatives are suboptimal. Novel approaches for improving awareness of the available screening guidelines are needed.

Rectal cancer in hereditary nonpolyposis colorectal cancer

BACKGROUND

Hereditary nonpolyposis colorectal cancer (HNPCC) accounts for approximately 2% to 5% of all colorectal cancers. Rectal cancer in HNPCC is not well characterized.

METHODS

A retrospective medical record review of HNPCC patients with colorectal cancer diagnosis from December 1948 to December 1999 was performed in an attempt to elucidate the natural history of rectal cancer in HNPCC. Group A consisted of patients diagnosed with rectal cancer as the index colorectal cancer. Group B consisted of patients diagnosed with rectal cancer as a metachronous colorectal cancer.

RESULTS

Twenty-five of 104 patients developed rectal cancer in our HNPCC registry. There were 18 patients in group A with a median age at diagnosis of rectal cancer of 48 years (range 24 to 79) and 7 patients in group B diagnosed at a median age of 58 years (range 45 to 68). Three of 18 patients (17%) in group A developed metachronous colon cancers at a median of 203 months (range 27 to 373) from the index rectal cancer. Rectal cancer in group B was diagnosed at a median 245 months (range 51 to 564) from the index colorectal cancer diagnosis.

CONCLUSIONS

Rectal cancer in HNPCC is not uncommon. The presentation of rectal carcinoma should not obviate the evaluation for HNPCC in suspected cases.

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.

Incidence of hereditary nonpolyposis colorectal cancer and the feasibility of molecular screening for the disease

BACKGROUND

Genetic disorders that predispose people to colorectal cancer include the polyposis syndromes and hereditary nonpolyposis colorectal cancer. In contrast to the polyposis syndromes, hereditary nonpolyposis colorectal cancer lacks distinctive clinical features. However, a germ-line mutation of DNA mismatch-repair genes is a characteristic molecular feature of the disease. Since clinical screening of carriers of such mutations can help prevent cancer, it is important to devise strategies applicable to molecular screening for this disease.

METHODS

We prospectively screened tumor specimens obtained from 509 consecutive patients with colorectal adenocarcinomas for DNA replication errors, which are characteristic of hereditary colorectal cancers. These replication errors were detected through microsatellite-marker analyses of tumor DNA. DNA from normal tissue from the patients with replication errors was screened for germ-line mutations of the mismatch-repair genes MLH1 and MSH2.

RESULTS

Among the 509 patients, 63 (12 percent) had replication errors. Specimens of normal tissue from 10 of these 63 patients had a germ-line mutation of MLH1 or MSH2. Of these 10 patients (2 percent of the 509 patients), 9 had a first-degree relative with endometrial or colorectal cancer, 7 were under 50 years of age, and 4 had had colorectal or endometrial cancer previously.

CONCLUSIONS

In this series of patients with colorectal cancer in Finland, at least 2 percent had hereditary nonpolyposis colorectal cancer. We recommend testing for replication errors in all patients with colorectal cancer who meet one or more of the following criteria: a family history of colorectal or endometrial cancer, an age of less than 50 years, and a history of multiple colorectal or endometrial cancers. Patients found to have replication errors should undergo further analysis for germ-line mutations in DNA mismatch-repair genes.

Hereditary nonpolyposis colorectal cancer associated with duodenal carcinoma: a case report

Hereditary nonpolyposis colorectal cancer is an autosomal, dominantly inherited disease, characterized by an early age of onset, right colon predominance and an association with various extracolorectal malignancies. We present a case of a 47-year-old woman who met the clinical criteria for the diagnosis of hereditary nonpolyposis colorectal cancer from her past and family histories. She had undergone operations for uterine cancer (histology not confirmed) at age 35 and for advanced cancer of the ascending colon at age 45. Gastroendoscopy revealed a flat elevated lesion, 20 mm in size, with a protrusion (type IIa + Is) in the second portion of the duodenum in March 1996. Additionally, colonoscopy showed a flat elevated lesion, 30 mm in size, with an irregular and nodular surface (type IIa, laterally spreading tumor) in the descending colon. After the operation, the resected specimen of the duodenum histologically showed a well-differentiated adenocarcinoma associated with a tubulo-villous adenoma which had invaded the submucosal layer. The tumor of the colon was histologically confirmed to be a moderately-differentiated adenocarcinoma with submucosal invasion. A high frequency of replication error positivity (4/5 loci) was detected in both of the tumors. Reports of early cancer of the duodenum, associated with extracolorectal malignancies in hereditary nonpolyposis colorectal cancer, are very rare in the literature. Although it is difficult to determine which extracolorectal tumor sites should be taken into consideration by screening programs, we believe that careful observation by upper gastrointestinal endoscopy, which includes the duodenum, is necessary for patients with hereditary nonpolyposis colorectal cancer.

Clinical features, frequency and prognosis of Dukes' A colorectal carcinoma: a population-based investigation

The main aim of this study was, through the data of a population-based Registry, to establish the incidence of Dukes' A lesions by year of registration and the main clinical features, and to assess cancer-specific survival. One hundred and eighteen Dukes' A colorectal tumours were diagnosed (in 117 patients) out of 1337 registered between 1984 and 1992 in the Health Care District of Modena, Northern Italy; 94 patients were treated with surgery and 23 with endoscopic polypectomy. The frequency of Dukes' A tumours ranged between 4.8% and 18% by year of registration. Dukes' A carcinomas were significantly more frequent in the distal colon. Only 5 patients (4%) died of their cancer, and in all patients the tumour was localised in the rectum. Carcinomas associated with a poor prognosis did not show any of the biological variables usually associated with an unfavourable outcome, but, our data suggest the possibility of incomplete removal of tumours at surgery.

Hereditary nonpolyposis colorectal cancer: review of clinical, molecular genetics, and counseling aspects

Lynch syndrome, or hereditary nonpolyposis colon cancer (HNPCC), is an autosomal-dominant disease accounting for approximately 1-5% of all colorectal cancer cases. Due to the lack of pathognomonic morphological or biomolecular markers, HNPCC has traditionally posed unique problems to clinicians and geneticists alike, both in terms of diagnosis and clinical management. Recently, novel insight into the pathogenesis of this syndrome has been provided by the identification of its molecular basis. In HNPCC families, germline mutations in any of four genes encoding proteins of a specialized DNA repair system, the mismatch repair, predispose to cancer development. Mutations in mismatch repair genes lead to an overall increase of the mutation rate and are associated with a phenotype of length instability of microsatellite loci. The present report summarizes the clinicopathological aspects of HNPCC and reviews the most recent molecular and biochemical findings.

The risk of brain tumours in hereditary non-polyposis colorectal cancer (HNPCC)

Hereditary non-polyposis colorectal cancer (HNPCC) is known to be associated with several extracolonic cancers, e.g., cancers of the endometrium, stomach, urinary tract, small bowel and ovary. An association between HNPCC and brain tumours has also been reported, although previous risk analysis did not reveal an excess of this type of tumour. To determine whether HNPCC predisposes patients to brain tumours, we used risk analysis to compare families with HNPCC to those in the general population. Of the 1,321 subjects from 50 HNPCC families (with 60,237 person-years of follow-up) in the Dutch HNPCC Registry which satisfy the Amsterdam Criteria, 312 had colorectal cancer. The registry revealed 14 brain tumours in the HNPCC-patients and their first-degree relatives: 5 astrocytomas, 3 oligodendrogliomas, 1 ependymoma and 5 tumours for which a pathological report was not available. The relative risk of brain tumour in patients with HNPCC and their first-degree relatives was 6 times greater than in the general population (95% confidence interval, 3.5 to 10.1). After exclusion of the cases based only on family history, the relative risk was 4.3 (95% confidence interval, 2.3 to 8.0). Although the relative risk of brain tumour was increased, the lifetime risk was low (3.35%). Because it is not certain whether an improvement of the overall prognosis can be achieved by early diagnosis and intervention, and in view of the low lifetime risk, we do not recommend screening for brain tumours in HNPCC families.

Genetic aspects of colorectal cancer: the surgeon's view

A characteristic feature of colorectal cancer genesis is its stepwise progression, which offers unique possibilities for studying its development. There are two principal kinds of mutation leading to uncontrolled cell proliferation and cancer. The first renders a stimulatory gene hyperactive--generation of an oncogene--and the second is the inactivation of a tumour suppressor gene. Current knowledge suggest that the change from normal mucosa to a small adenoma may be mediated by mutations of the APC gene and MCC gene on chromosome 5, by chromosome 5 deletion, by c-myc activation, and by DNA hypomethylation. The development to a large adenoma may be caused by Ki-ras mutation and further change to a dysplastic adenoma by deletion of the DCC gene on chromosome 18. The ability to become an invasive carcinoma may then be mediated by p53 mutations and deletion of chromosome 17p. Identification of genetic markers for metastatic disease is under progress.

Prophylaxis against colorectal cancer

Colorectal cancer is diagnosed in more than 3000 people every year in Denmark, with a population of 5 million, and 2000 die from this disease every year. The aetiology of the disease is complex, but an increasing number of cancers have been related to genetics and Denmark is contributing with a well-established register of familial adenomatous polyposis and a recently founded register for hereditary nonpolyposis colorectal cancer, both with major international relationships. The Danish tradition of epidemiology and clinical trials has also been demonstrated in population screening trials for colorectal cancer in average-risk persons as well as high-risk groups with precursors of the disease. The present review places Danish contributions within the prophylaxis of colorectal cancer during the last decade in an international context.