Attenuated familial adenomatous polyposis and Muir-Torre syndrome linked to compound biallelic constitutional MYH gene mutations

Attenuated familial adenomatous polyposis and Muir-Torre syndrome linked to compound biallelic constitutional MYH gene mutations.Peculiar dermatologic manifestations are present in several heritable gastrointestinal disorders. Muir-Torre syndrome (MTS) is a genodermatosis whose peculiar feature is the presence of sebaceous gland tumors associated with visceral malignancies. We describe one patient in whom multiple sebaceous gland tumors were associated with early onset colon and thyroid cancers and attenuated polyposis coli. Her family history was positive for colonic adenomas. She had a daughter presenting with yellow papules in the forehead region developed in the late infancy. Skin and visceral neoplasms were tested for microsatellite instability and immunohistochemical status of mismatch repair (MMR), APC and MYH proteins. The proband colon and skin tumors were microsatellite stable and showed normal expression of MMR proteins. Cytoplasmic expression of MYH protein was revealed in colonic cancer cells. Compound heterozygosity due to biallelic mutations in MYH, R168H and 379delC, was identified in the proband. The 11-year-old daughter was carrier of the monoallelic constitutional mutation 379delC in the MYH gene; in the sister, the R168H MYH gene mutation was detected. This report presents an interesting case of association between MYH-associated polyposis and sebaceous gland tumors. These findings suggest that patients with MTS phenotype that include colonic polyposis should be screened for MYH gene mutations.

Subcellular localization of beta-catenin and APC proteins in colorectal preneoplastic and neoplastic lesions

Adenomatous polyposis coli (APC) is a tumor suppressor gene whose main function is the destabilization of beta-catenin, a key effector of the Wnt signaling pathway. This gene is defective in familial adenomatous polyposis (FAP), a dominantly inherited disease, but inactivation of APC has been reported also in most sporadic colorectal tumors and it is considered an early event in colorectal tumorigenesis. The aim of the present study was to evaluate the intracellular ultrastructural distribution of beta-catenin and APC proteins in epithelial cells of normal colorectal mucosa, aberrant crypt foci (ACF, an early premalignant lesion) and cancer. We used the immunogold electron microscopic method to identify both proteins. Normal colonic epithelial cells showed a strong membranous expression of beta-catenin and lacked cytoplasmic and nuclear expression. Normal cells showed APC localization pattern characterized by diffuse nuclear expression and along the plasma membrane. In ACF and in carcinoma an absent or reduced membranous expression of beta-catenin was associated with an increased nuclear and cytoplasmatic expression. In aberrant crypt foci and carcinoma, APC was evident inside the nucleus and at the level of cell-cell junctions, but it was decreased in the cytoplasm. This method allowed the accurate localization of proteins of the Wnt signaling pathway in the early steps of colorectal carcinogenesis. The similar pattern of subcellular distribution of APC and beta-catenin in dysplastic ACF and colorectal cancer suggests that ACF are precursor lesions of sporadic and FAP-associated colorectal carcinoma.

Molecular genetic alterations and clinical features in early-onset colorectal carcinomas and their role for the recognition of hereditary cancer syndromes

OBJECTIVES

Colorectal cancer (CRC) occurs rarely in young individuals (<45 yr) and represents one of the criteria for suspecting hereditary cancer families. In this study we evaluated clinical features and molecular pathways (chromosomal instability [CIN] and microsatellite instability [MSI]) in early-onset CRC of 71 patients.

METHODS

Detailed family and personal history were obtained for each patient. Expression of APC, beta-catenin, p53, MLH1, MSH2, and MSH6 genes was evaluated by immunohistochemistry. MSI analysis was performed and constitutional main mutations of the mismatch repair (MMR) genes were searched by gene sequencing.

RESULTS

Fourteen (19.7%) out of the 71 cases showed both MSI and altered expression of MMR proteins. In the 57 MSI-negative (MSI-) lesions altered expression of APC, beta-catenin, and p53 genes were found more frequently than in MSI-positive(MSI+) tumors. Seven (50%) out of the 14 patients with MSI+ tumors presented clinical features of Lynch syndrome (hereditary non-polyposis colorectal cancer [HNPCC]) and in all but one, constitutional mutations in MLH1 or MSH2 genes could be detected. The same mutations were also found in other family members.

CONCLUSIONS

Our study demonstrates the involvement of CIN in a majority of early-onset colorectal tumors. Furthermore, we identified Lynch syndromes in seven cases (50%) of early-onset colorectal carcinomas with impairment of the MMR system. These results suggest that patients with early-onset CRC should be screened for hereditary cancer syndrome through clinical and molecular characterizations.

Different phenotypes in Muir-Torre syndrome: clinical and biomolecular characterization in two Italian families

The Muir-Torre syndrome (MTS) is an autosomal dominant genodermatosis characterized by the presence of sebaceous gland tumours, with or without keratoacanthomas, associated with visceral malignancies. We describe and characterize two families in which the ample phenotypic variability of MTS was evident. After clinical evaluation, the skin and visceral tumours of one member of a family with 'classic' MTS and one member of a family with a 'peculiar' MTS phenotype without sebaceous lesions, but with only multiple keratoacanthomas, were analysed for microsatellite instability (MSI) and by immunohistochemistry. Tumours of both individuals showed MSI, with a concomitant lack of MSH2 immunostaining in all evaluated skin and visceral lesions; moreover, in the proband of family 2 a constitutional mutation (C-->T substitution leading to a stop codon) in the MSH2 gene was identified. We conclude that the diagnosis of MTS, which is mainly clinical, should take into account an ample phenotypic variability, which includes both cases with typical cancer aggregation in families and cases characterized by the association of visceral malignancies with multiple keratoacanthomas (without sebaceous lesions), without an apparent family history of cancer.

Local recurrences of rectal cancer

Data from cancer registries show that incidence of rectal cancer is still high in Italy, while mortality rates are slightly decreasing in most recent years. Surgery is the treatment of choice and in most cases with curative intent. The rectum may be defined as the tract of the large bowel distal to 12 cm from the anal verge. Tumors located in that segment show local recurrence rates higher than those for tumors located proximally. Pelvic recurrence is evident as a regrowth of cancer in and around the tumor bed. Powerful imaging techniques have been developed for the early and appropriate evaluation of pelvic recurrences. A wide range of recurrence rates after operation for rectal cancer are reported, spanning from 3% to over 30%. The main determinants of local recurrence are related to the tumor and to the treatment. Among the former, stage at diagnosis and number of lymph nodes involved are the most important, along with inadvertent perforation of the intestine and location of tumor in the rectum. Among treatment factors, type of operation and experience of the operator should be mentioned. A major advancement in rectal surgery has been the implementation of total excision of the mesorectum. This technique has decreased dramatically recurrence rates of rectal cancer, though increasing the risk of local complications. Preoperative radiotherapy seems to confer a slight further advantage in selected cases. Management of locally recurrent tumors is still unsatisfactory and surgery is feasible only in less than 10% of cases.

Incidence and survival of patients with Dukes' A (stages T1 and T2) colorectal carcinoma: a 15-year population-based study

BACKGROUND AND AIMS

Patients with stage I (Dukes' A) colorectal carcinoma tend to show a good prognosis; however, recurrences can be observed in some patients. Through a specialized colorectal cancer Registry, we attempted to investigate the epidemiological and clinical features of individuals with Dukes' A neoplasms.

PATIENTS AND METHODS

From 1984 to 1998, 295 individuals were diagnosed with Stage I /Dukes' A tumors; 150 of these had lesions infiltrating the muscular wall (T2), while 145 had neoplasms limited to the submucosa (T1).

RESULTS

Dukes' A tumors represented 13.8% of all registered neoplasms; the percentage doubled over the study period (8.1% in the first year vs. 16.8% in the final year). In each year of observation, the preferential locations were the rectum and sigmoid colon (75% of all lesions). Most patients required surgery, but only 21.3% could be managed by endoscopic polypectomy. Overall 5-year survival was 81.0% (82.1% in T1, 80.0% in T2). Recurrences were seen in 6.8% (2.8% in T1, 10.7% in T2), while 36 patients (12.2%) died of causes unrelated to colorectal cancer. In 17 out of 20 patients who died of cancer, the lesions were localized in the rectosigmoid region. Survival analysis showed a significantly better prognosis (P<0.007) for patients with T1 tumors.

CONCLUSIONS

The proportion of stage I colorectal tumors tended to increase over time. Although the overall prognosis is good in four-fifths of the cases, approximately one-fifth of these patients die of recurrent disease or of other causes. As expected, the prognosis was significantly more favorable for patients with T1 lesions. For patients with T2 tumors, radical surgery is the most appropriate approach.

Hereditary nonpolyposis colorectal cancer: an approach to the selection of candidates to genetic testing based on clinical and molecular characteristics

OBJECTIVE

Identification of clinical and molecular characteristics associated with constitutional MLH1 and MSH2 mutations and definition of a stepwise strategy for the selection of colorectal cancer (CRC) patients amenable to MLH1 and MSH2 genetic testing.

METHODS

90 unrelated CRC patients were initially selected on the basis of either familial or early onset occurrence of CRC. They were screened for the presence of constitutional MLH1 and MSH2 mutations and for microsatellite instability (MSI).

RESULTS

16 pathogenetic mutations (9 MLH1 and 7 MSH2) were identified in 41% of Amsterdam hereditary nonpolyposis colorectal cancer (HNPCC) families, 5% of suspected HNPCC families, and 14% of sporadic early-onset CRC patients. The presence of the mutations correlated with MSI, with early age of onset and proximal location of the tumor, and with the presence of some extracolonic tumors of the HNPCC spectrum and/or multiple tumors in the family.

CONCLUSIONS

Evaluation of clinical and molecular characteristics is useful for the identification of candidates to MLH1 and MSH2 mutational analysis and allows the application of a rational approach to genetic testing.

Identification of Muir-Torre syndrome among patients with sebaceous tumors and keratoacanthomas

BACKGROUND

The Muir-Torre syndrome (MTS) is an autosomal-dominant genodermatosis characterized by the presence of sebaceous gland tumors, with or without keratoacanthomas, associated with visceral malignancies. A subset of patients with MTS is considered a variant of the hereditary nonpolyposis colorectal carcinoma, which is caused by mutations in mismatch-repair genes. The objective of the current study was to evaluate whether a combined clinical, immunohistochemical, and biomolecular approach could be useful for the identification of Muir-Torre syndrome among patients with a diagnosis of sebaceous tumors and keratoacanthomas.

METHODS

The authors collected sebaceous skin lesions and keratoacanthomas recorded in the files of the Pathology Department of the University of Modena during the period 1986-2000. Through interviews and examination of clinical charts, family trees were drawn for 120 patients who were affected by these skin lesions.

RESULTS

Seven patients also were affected by gastrointestinal tumors, thus meeting the clinical criteria for the diagnosis of MTS. In the MTS families, a wide phenotypic variability was evident, both in the spectrum of visceral tumors and in the type of skin lesions. Microsatellite instability was found in five MTS patients: These patients showed concordance with immunohistochemical analysis; moreover, a constitutional mutation in the MSH2 gene was found in 1 patient. Lack of expression of MSH2/MSH6 or MLH1 proteins was evident in the skin lesions and in the associated internal malignancies of 3 patients and 2 patients with MTS, respectively.

CONCLUSIONS

The clinical, biomolecular, and immunohistochemical characterization of sebaceous skin lesions and keratoacanthomas may be used as screening for the identification of families at risk of MTS, a disease that is difficult to recognize and diagnose.

Relationship between MUC5AC and altered expression of MLH1 protein in mucinous and non-mucinous colorectal carcinomas

The main purpose of this study was to examine the expression of mucins and mismatch repair proteins in colorectal carcinomas. The immunohistochemical distribution of apomucins MUC2, MUC5AC, and the expression of MLH1 and MSH2 proteins were examined in 76 mucinous and 60 non-mucinous colorectal carcinomas. MUC2 was noted in all mucinous carcinomas, whereas MUC5AC was present in 41 cases only (54%). In non-mucinous carcinomas, MUC2 was expressed in 61.7% of the tumors; by contrast, MUC5AC was present in 20% of the cases. The expression level of apomucins was significantly different in mucinous and non-mucinous lesions (p<0.001). Twenty-seven (35.5%) of the mucinous carcinomas showed no MLH1 expression, whereas 11 (18.3%) of the non-mucinous tumors did. This difference was statistically significant (p<0.005). Altered expression of MSH2 protein was never observed. The lack of MLH1 expression was considerably more frequent in carcinomas with secretion of MUC5AC (p<0.005). Our study has demonstrated this close relationship by immunohistochemical methods. In summary, our data show: (1) differences in the expression of mucins between mucinous and non-mucinous tumors; (2) a high frequency of altered MLH1 protein expression (35.5%) in mucinous carcinomas; (3) a significant relationship between the presence of MUC5AC and the altered expression of MLH1 protein in colorectal carcinomas.

Trend of incidence, subsite distribution and staging of colorectal neoplasms in the 15-year experience of a specialised cancer registry

BACKGROUND

Two-thirds of colorectal malignancies are localised in the left colon and rectum. Recent studies suggest a trend towards an increase of right-sided tumours which might have important implications for screening and surveillance. A colorectal cancer registry was set up in Modena, northern Italy, with the purpose of examining incidence, subsite distribution and staging of colorectal malignancies over a 15-year period.

PATIENTS AND METHODS

From 1984 to 1998, 2517 tumours in 2462 patients were detected and staged with the tumour node metastasis (TNM) system. The 'right colon' was considered from caecum to splenic flexure; the 'left colon' included descending and sigmoid colon; and the 'rectum' included rectosigmoid junction, ampulla and anus.

RESULTS

Cancer incidence showed an overall increase. Considering the various subsites, an increase of 33.7% in all colonic segments was shown whereas rectal tumours tended to decline. TNM staging showed a gradual increase of localised lesions (41.2% in 1984 versus 53.3% in 1998), with a proportional reduction of advanced tumours.

CONCLUSIONS

Our study indicates an increase of tumour incidence in all colonic segments more than a shift to the right colon. TNM staging tended to improve with an appreciable increase of localised lesions. These findings could be consequent to a more extensive use of colonoscopy.

Genetic testing among high-risk individuals in families with hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC) is frequently associated with constitutional mutations in a class of genes involved in DNA mismatch repair. We identified 32 kindreds, with germline mutations in one of three genes hMSH2, hMLH1 or hMSH6. In this study, we purposed to evaluate how many high-risk individuals in each family underwent genetic testing: moreover, we assessed how many mutation-positive unaffected individuals accepted colonoscopic surveillance and the main findings of the recommended follow-up. Families were identified through a population-based registry, or referred from other centres. Members of the families were invited for an education session with two members of the staff. When a kindred was consistent with HNPCC, neoplastic tissues were examined for microsatellite instability (MSI) and immunohistochemical expression of MSH2, MLH1 and MSH6 proteins. Moreover, constitutional mutations were searched by SSCP or direct sequencing of the whole genomic region. Of the 164 subjects assessed by genetic testing, 89 were gene carriers (66 affected - that is, with HNPCC-related cancer diagnosis - and 23 unaffected) and 75 tested negative. Among the 23 unaffected gene carriers, 18 (78.3%) underwent colonoscopy and four declined. On a total of 292 first degree at risk of cancer, 194 (66.4%) did not undergo genetic testing. The main reasons for this were: (a) difficulty to reach family members at risk, (b) lack of collaboration, (c) lack of interest in preventive medicine or 'fatalistic' attitude towards cancer occurrence. The number of colorectal lesions detected at endoscopy in gene carriers was significantly (P<0.01) higher than in controls (noncarriers). We conclude that a large fraction of high-risk individuals in mutation-positive HNPCC families does not undergo genetic testing, despite the benefits of molecular screening and endoscopic surveillance. This clearly indicates that there are still barriers to genetic testing in HNPCC, and that we are unable to provide adequate protection against cancer development in these families.

Aetiology of colorectal cancer and relevance of monogenic inheritance

BACKGROUND AND AIMS

Although diet and lifestyle are associated with the development of colorectal malignancies, the only clearly identified aetiological factors in colorectal cancer are inheritance (hereditary non-polyposis colorectal cancer (HNPCC) and familial polyposis), inflammatory bowel diseases, papillomavirus, and acquired immunodeficiency syndrome (AIDS). Our aim was to determine what proportion of colorectal neoplasms could be attributed to these specific factors.

PATIENTS AND METHODS

Data from a colorectal cancer registry were analysed over a 15 year period, during which nearly 2500 cases were recorded. In patients with suspected HNPCC, microsatellite instability and immunohistochemical expression of proteins encoded by the main DNA mismatch repair genes were assessed. In families with unstable neoplasms, constitutional mutations of the mismatch repair genes hMSH2, hMLH1, and hMSH6 were evaluated by single strand conformation polymorphism analysis and sequencing.

RESULTS

Inflammatory bowel diseases, familial polyposis, and AIDS were rare causes of colorectal cancer (three, three, and one case, respectively). Anal squamous carcinoma developed in 27 patients (1.0%) and could be attributed to papillomavirus infection. In 58 patients (from 34 families) a clinical diagnosis of HNPCC was established (2.4%). In total, cases with a known aetiology were 92 (3.7% of all patients). Microsatellite instability was detected in 15 cancers from HNPCC families, and germline mutations in six families (12 patients, 0.5% of the total). Families with unstable tumours, with or without mutations, were clinically similar, suggesting the involvement of the mismatch repair system even when mutations were not detected.

CONCLUSIONS

The study suggests that the aetiology of colorectal malignancies remains elusive in the large majority of cases. Among specific causes, HNPCC represents the most frequent. However, with a population based approach, constitutional mutations of the main genes involved in HNPCC can be detected in only 20% of cases.

Aberrant crypt foci in colorectal carcinogenesis. Cell and crypt dynamics

Aberrant crypt foci (ACF) have been identified on the colonic mucosal surface of rodents treated with colon carcinogens and of humans after methylene-blue staining and observation under a light microscope. Several lines of evidence strongly suggest that ACF with certain morphological, histological, cell kinetics, and genetic features are precursor lesions of colon cancer both in rodents and in humans. Thus, ACF represent the earliest step in colorectal carcinogenesis. This paper has the main purpose of reviewing the evidence supporting this view, with particular emphasis on cell and crypt dynamics in ACF. ACF have been used as intermediate biomarkers of cancer development in animal studies aimed at the identification of colon carcinogens and chemopreventive agents. Recently, evidence has also shown that ACF can be effectively employed in chemopreventive studies also in humans.

Phenotype-genotype correlations in an extended family with adenomatosis coli and an unusual APC gene mutation

PURPOSE

Genotype-phenotype correlations in familial adenomatous polyposis are only partially understood and, in particular, little is known about the biomolecular characteristics of desmoid tumors, which are one of the most serious and frequent manifestations of familial adenomatous polyposis. In the present study, we describe a family with familial adenomatous polyposis, with peculiar clinical characteristics (i.e., frequency and severity of desmoid neoplasms) associated with an unusual mutation of the adenomatosis polyposis coli gene. If confirmed by other investigations, these findings might help to understand the biologic mechanisms by which specific adenomatosis polyposis coli mutations predispose to desmoid tumors.

METHODS

The family with familial adenomatous polyposis, living in southern Italy, was studied from 1985 to the end of 1999; at this date, 15 individuals have been affected by histologically verified familial adenomatous polyposis, 11 of whom had desmoid tumors. A total of 19 family members were studied for adenomatosis polyposis coli gene mutations; 13 of them tested positive and 6 negative. The analytical procedure-previously described-consisted of the extraction of peripheral blood cell DNA, amplification of exon 15 by polymerase chain reaction, single-strand conformation polymorphism analysis, and direct sequencing of the DNA fragment containing the mutation.

RESULTS

The main clinical features of the family were 1) a high frequency of desmoid tumors and, consequently, a high penetrance of the desmoid trait in all branches of the family and in 11 (73.3 percent) of 15 affected individuals and 2) severity of desmoids in at least 4 family members, 2 of whom died for causes related to the presence of these tumors. The molecular basis of the disease was an uncommon mutation of the adenomatosis polyposis coli gene, consisting of a large deletion of 310 base pairs at codon 1,464, with duplication of the breakpoint (4,394ins15del310), leading to a stop codon at position 1,575.

CONCLUSIONS

The present study shows that a truncating mutation in the adenomatosis polyposis coli gene at the beginning of the region frequently associated with desmoids induced a familial adenomatous polyposis phenotype featured by a high penetrance of the desmoid trait, with severe disease in several affected members of both sexes. The study may help to understand the biologic mechanisms of genotype-phenotype correlations in adenomatosis coli.

Molecular screening for hereditary nonpolyposis colorectal cancer: a prospective, population-based study

PURPOSE

Germline mutations in mismatch repair genes predispose to hereditary nonpolyposis colorectal cancer (HNPCC). To address effective screening programs, the true incidence of the disease must be known. Previous clinical investigations reported estimates ranging between 0.5% and 13% of all the colorectal cancer (CRC) cases, whereas biomolecular studies in Finland found an incidence of 2% to 2.7% of mutation carriers for the disease. The aim of the present report is to establish the frequency of the disease in a high-incidence area for colon cancer.

PATIENTS AND METHODS

Through the data of the local CRC registry, we prospectively collected all cases of CRC from January 1, 1996, through December 31, 1997 (N = 391). Three hundred thirty-six CRC cases (85.9% of the incident cases) were screened for microsatellite instability (MSI) with six to 12 mono- and dinucleotide markers. MSI cases were subjected to MSH2 and MLH1 germline mutation analysis and immunohistochemistry; the methylation of the promoter region was studied for MLH1.

RESULTS

Twenty-eight cases (8.3% of the total) showed MSI. MSI cases differed significantly from microsatellite-stable (MSS) cases for their proximal location (P <.01), high mucinous component (P <.01), and poor differentiation (P =.002). Of MSI cases studied (n = 12), only one with a family history compatible with HNPCC had a germline mutation (in MSH2). Five other patients with a family history of HNPCC (two with MSI and three with MSS tumors) did not show germline mutations.

CONCLUSION

We conclude that the incidence of molecularly confirmed HNPCC (one [0.3%] of 336) in a high-incidence area for CRC is lower than in previous biomolecular and clinical estimates.

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.

Methylation pattern of different regions of the MLH1 promoter and silencing of gene expression in hereditary and sporadic colorectal cancer

Nonrandom, widespread promoter methylation of tumor suppressor genes is a common mechanism of gene inactivation during tumorigenesis. We examined the methylation status of two distinct regions of the MLH1 promoter (proximal and distal to the transcription start site) and the MLH1 gene expression by methylation-specific PCR and immunohistochemistry. A total of 72 colorectal tumors, both with (n = 51, 22 affected by hereditary nonpolyposis colorectal cancer, HNPCC, defined according to the international clinical criteria and 29 sporadic cases) and without microsatellite instability (MSI) (n = 21) were studied. Methylation was present in at least one of the two promoter regions in 86% of the sporadic MSI cases, in 33% of the cases lacking MSI, and in 23% of the HNPCC tumors. In the HNPCC cases with a known MLH1 mutation (n = 10) none of the two promoter regions was methylated. Hypermethylation in both MLH1 promoter regions was seen in 45% of the MSI sporadic cases vs. 5% of the MSI-negative cases and 0% of the HNPCC cases. The overall concordance between the two promoter regions regarding methylation status was good (P = 0.009), but no significant correlation between methylation and suppression of the MLH1 immunohistochemical expression was found. Our data confirm that mutation and hypermethylation are mutually exclusive mechanisms in inducing mismatch repair deficiency and support the hypothesis of methylation as a process evenly distributed along the different regions of the promoter.

Microsatellite instability and mismatch-repair protein expression in hereditary and sporadic colorectal carcinogenesis

Aberrant crypt foci (ACF) are microscopic clusters of altered colonic crypts considered premalignant lesions in the large bowel. Genomic instability at short tandem repeats in the DNA, referred to as microsatellite instability (MSI) is the hallmark of hereditary nonpolyposis colorectal carcinoma (HNPCC) caused by mutations in DNA mismatch-repair genes, mostly hMLH1 and hMSH2. In this study, we evaluated for MSI ACF (n = 16), adenomas (n = 18), carcinomas (n =22), and lymph node metastases (n = 3) from 17 patients with colorectal cancer positive for MSI. Ten patients were members of HNPCC families; 7 patients had no family history of cancer. MSI was found in 7 of 7 (100%) ACF and 11 of 12 (91%) adenomas from patients with HNPCC. MSI was not related to histology and size of ACF. A progressive increase in instability as estimated by the number of shifted bands was observed along the ACF-adenoma-carcinoma sequence. In contrast, two of nine (22%) ACF and none of six adenomas from patients with MSI sporadic carcinoma were unstable at microsatellite loci. hMLH1 or hMSH2 protein expression was altered only in MSI-positive premalignant lesions (ACF and/or adenomas), but not in all MSI-positive lesions in patients with HNPCC. These observations provide evidence of the premalignant nature of ACF in HNPCC and suggest that MSI is a very early event both in HNPCC and in sporadic colorectal carcinogenesis, although in the latter it seems infrequent.

Problems in the identification of hereditary nonpolyposis colorectal cancer in two families with late development of full-blown clinical spectrum

The recognition of Hereditary Nonpolyposis Colorectal Cancer (HNPCC) remains difficult despite the most recent advancements of molecular biology and technology. We describe two families with early onset of cancer but no suspicion of hereditary tumors; during follow-up, both families developed a tumor spectrum highly suggestive of HNPCC, thus emphasizing the importance of family history for a proper identification of hereditary tumors or cancer aggregation. Microsatellite instability was negative in tumors from both families and, as expected, no germline mutations of the major DNA mismatch repair genes (MSH2 and MLH1) could be detected. Suspicion of the disease at the time of proband's lesion might have led to prevention, or early diagnosis, of at least three malignant tumors. We conclude that a possible genetic origin should always be suspected in individuals with early-onset neoplasms of the large bowel and probably of other organs such as the endometrium, small bowel, and urothelium, even when the initial pedigree does not show marked aggregation of cancers or vertical transmission.

Staging and survival of colorectal cancer: are we making progress? The 14-year experience of a Specialized cancer Registry

BACKGROUND AND AIMS

It is still unclear whether recent advancements in colorectal cancer research have led to an improvement in management and prognosis of the disease. Through the data of a specialized colorectal cancer Registry we aimed at analysing pathological staging and 5-year survival of all patients with malignancies of large bowel diagnosed between 1984 and 1997. Main objective was to ascertain whether or not we are making progress in the control of this common neoplasm.

PATIENTS AND METHODS

During the 14-year period 1984-97, a total of 2,240 colorectal cancer patients were registered, for a crude incidence rate of 64.5 and 55.2/100,000/year in males and females, respectively Tumours were staged with "Tumour, Node, Metastasis" system, corresponding to Dukes' classification, into four main groups. Survival was assessed with Life Table analysis, and statistical significance--between various subgroups--evaluated with Log-Rank Test.

RESULTS

Crude incidence rates of colorectal neoplasms showed minor fluctuations during initial period of registration, increasing sharply after 1990 mainly due to localized (stage I and II) lesions and, to a lesser degree, to stage III tumours. Number of advanced (stage IV and unstaged) malignancies remained virtually stable. When results were expressed as percent of total cases, the fraction of localized lesions increased from 39% in the biennium 1984-5 to 51.6% in 1986-97, and the proportion of advanced tumours fell from 39% to 21.6% (p for trend <0.001). As expected, 5-year survival was significantly (p<0.002) more favourable for individuals diagnosed in 1990-91 than for patients registered in 1984-89.

CONCLUSIONS

In Northern Italy, incidence rates of colorectal carcinoma are rising. This trend is associated with a sharp increase of newly detected localized lesions and with a significant improvement of overall 5-year survival. The result may be attributed to several concomitant factors, such as: A] wider use of colonoscopy, B) increased education of patients, C) more attention given to symptoms.

Genomic instability and target gene mutations in colon cancers with different degrees of allelic shifts

Two grades (high and low) of microsatellite instability (MSI) are known, depending on the number of mutated markers and the amount of allelic shifts. Forty-two colorectal tumors, previously found to have high-degree MSI at dinucleotidic repeat loci, were revisited with BAT26, a mononucleotide marker, and the number of shifted bases were counted. Seven tumors, all with local stages at diagnosis, had < or =6-bp deletions and consistently displayed shorter shifts also with other intronic mononucleotide markers. Analysis of mononucleotide tracts in the coding regions of MSH3, MSH6, BAX, and TGFbetaRII in the groups with large (>6 bp) and short (< or =6 bp) allelic shifts showed specific patterns of involvement for the individual genes: TGFbetaRII displayed a uniformly high rate of mutations, while MSH3, MSH6, and BAX were less frequently altered in tumors with short shifts. Our findings suggest that microsatellite instability arises gradually, evenly involving loci with similar features of length and repetition. However, target genes have a specific timing of mutation in this process: TGFbetaRII is involved in the early phases, while BAX and MSH6 are frequently associated with big size shifts and tumors with more advanced stages.

Clinical features and genotype-phenotype correlations in 41 Italian families with adenomatosis coli

BACKGROUND

Familial Adenomatous Polyposis in an autosomal dominant disease in which the large bowel is carpeted by polyps of various dimensions appearing during the second or third decade of life. Several extracolonic manifestations complete the clinical spectrum of Familial Adenomatous Polyposis. If untreated, the disease leads invariably to colorectal cancer. The gene responsible for the disease, adenomatous Polyposis Coli, has been localized at chromosome 5q21.

AIMS

To describe the clinical features of 156 Familial Adenomatous Polyposis patients (from 41 families) and to analyze possible correlations between genotype and phenotype.

PATIENTS AND METHODS

Familial Adenomatous Polyposis was defined as the presence of 100 or more polyps in the large bowel. In 17 families (41%), the proband was the only affected individual (single cases). Adenomatous Polyposis Coli gene mutations were studied on DNA extracted from peripheral white blood cells and evaluated by polymerase chain reaction single strand conformation polymorphism, followed by direct sequencing of samples showing abnormal banding at single strand conformation polymorphism.

RESULTS

The large majority of Familial Adenomatous Polyposis patients underwent surgery; colectomy with ileorectal anastomosis was the most frequent approach, however, cancer of the rectal stump developed in 11.6% of patients submitted to colectomy and ileorectal anastomosis. Adenomas were rare in the stomach (8.8%), but their frequency increased in the duodenum (33.8%) and jejunum (55.0%, chi 2 for trend 23.7, p < 0.001). Desmoid tumours were diagnosed in 17 patients (10.9% of the total) and in 6 families. Mutations of the Adenomatous Polyposis Coli gene were studied in 20 out of 25 families (80%) and on a total of 75 individuals. The most frequent alterations were 1 to 5 bp deletions leading to stop codons and truncated proteins. Desmoid tumours, presence of duodenal or jejunal adenomas were associated with an ample range of mutations, from codon 215 to codon 1464. In contrast, particularly severe polyposis (mean age at appearance of polyps 11-16 years, and of cancer development 27-32 years) was associated with a "hotspot" mutation site at codons 1303-1309.

CONCLUSIONS

In patients with Familial Adenomatous Polyposis, subtotal colectomy with ileorectal anastomosis is still the treatment of choice. Adenomatous lesions seem to show a "gradient" distribution from the stomach to the large bowel. Desmoid tumours are relatively common, though their incidence is limited to some of the families. Constitutional mutations can be detected in 80% of the investigated families. Genotype-phenotype correlations showed a hot-spot at codons 1303-1309, frequently associated with severe polyposis.

Clinical and molecular diagnosis of hereditary non-polyposis colorectal cancer: problems and pitfalls in an extended pedigree

Hereditary non-polyposis colorectal cancer (or Lynch syndrome) is an autosomal dominant disease in which early onset colorectal carcinomas aggregate in families together with tumours of other organs. The genetic basis of the syndrome has been clarified with the identification of mutations in several DNA mismatch repair genes (MSH2, MLH1, PMS1, PMS2 and MSH6). We describe the clinical features and molecular characterization of a large hereditary non-polyposis colorectal cancer family which has been followed for almost 10 years. The kindred showed a striking aggregation of colorectal tumours in 3 successive generations; most of these neoplasms developed before the age of 50 years and were localized in the proximal colon. Molecular tests (carried out in ten individuals) showed specific alterations at the MLH1 gene, consisting in the insertion of a T nucleotide between bases 2,269 and 2,270; the mutation caused frameshift of the open reading frame and synthesis of a polypeptide longer than normal. The only tumour that could be analysed was positive for microsatellite instability. Physicians should become more confident with hereditary tumours and their implications, which are not limited to a single individual but concern all family members at risk of cancer. This family approach is different, and requires more expertise than the traditional individual approach. Common problems encountered in Hereditary Non-polyposis Colorectal Cancer families include: A) poor collaboration of subjects at risk (a situation which may cause some conflict between the doctor's duty to inform patients about their risk of disease and the rights of patients to choose and decide about their health); B) definition of the most appropriate surveillance programme for a given family (how many investigations to propose to the patients, and how often); C) possible interaction between genes and environmental factors (for instance, a gene carrier--in this family--developed an endometrial carcinoma after standard tamoxifen adjuvant therapy for breast cancer).

Hereditary colorectal cancer in the general population: from cancer registration to molecular diagnosis

BACKGROUND

Hereditary non-polyposis colorectal cancer (HNPCC) is one of the most common inherited disorders predisposing to cancer. The genes responsible for the disease have recently been cloned and characterised; their mutations induce a generalised genomic instability which is particularly evident at microsatellite loci (replication error (RER)+ phenotype).

AIMS

To investigate how to select individuals and families in the general population who should be screened for constitutional mutations predisposing to colorectal cancer.

PATIENTS/METHODS

Between 1984 and 1995, 1899 colorectal malignancies in 1831 patients were registered, and in 1721 of these (94%), family trees could be obtained. Patients and families were classified into five categories according to a more or less likely genetic basis: HNPCC; "suspected" HNPCC; juvenile cases; aspecific cancer aggregation; sporadic cases. In 18 families with HNPCC as well as in 18 with suspected HNPCC, microsatellite instability in tumour tissues and constitutional mutations of two DNA mismatch repair genes (MSH2 and MLH1) could be evaluated. RER status was studied with five markers (BAT40, D2S123, D18S57, D17S787, and BAT26) in paraffin embedded tissues. Germline mutations of MSH2 or MLH1 genes were assessed on DNA and RNA extracted from lymphomonocytic cells, using reverse transcription polymerase chain reaction, single strand conformation polymorphism analysis, and direct DNA sequencing.

RESULTS

HNPCC represented 2.6% and suspected HNPCC 4.6% of all registered colorectal neoplasms. Eleven out of 18 HNPCC families (61%) showed microsatellite instability as opposed to four (of 18) suspected HNPCC (22%; p<0.02). Three germline mutations (two in MSH2 and one in MLH1 gene) were found in three different large HNPCC families, whereas no mutations were detected in suspected HNPCC.

CONCLUSIONS

In this study of cancer genetic epidemiology, data from a tumour registry were analysed and this ultimately led to the identification and selection of families that should be tested for mutator gene mutations. With the use of a population based approach, the incidence of mutations was appreciably lower than previously reported and limited to families with full blown HNPCC. It is possible that in most families with a clinical spectrum of HNPCC (or suspected HNPCC) other DNA mismatch repair genes are involved in the pathogenesis of the disease.

Epidemiologic and genetic factor in colorectal cancer: development of cancer in dizygotic twins in a family with Lynch syndrome

Human tumours usually develop due to a close interaction between environmental and genetic factors. This concept applies also to well defined genetic diseases such as Hereditary Nonpolyposis Colorectal Cancer (HNPCC or Lynch syndrome), which is featured by early onset tumours of the large bowel (and other target organs), striking aggregation of neoplasms in families, and vertical transmission consistent with an autosomal dominant pattern of inheritance. As a further example of gene/environment interaction, we report on a Hereditary Nonpolyposis Colorectal Cancer family in which two dizygotic twins were affected by cancer of the large bowel. One of the twins was slightly overweight and showed many common risk factors for colorectal carcinoma; he developed a Dukes' C lesion at the age of 52 years. The other twin was not overweight and was much less exposed to exogenous risk factors; a Dukes' B carcinoma was diagnosed at age 60, during a control endoscopy. This anedoctal report suggests that diet and lifestyle are of relevance also in patients with genetically determined tumours of the large bowel. It follows that the control of these environmental factors might be associated with a delay of tumour occurrence and possibly with a less aggressive tumour behaviour.

Microsatellite instability in multiple colorectal tumors

Tumor multiplicity is a hallmark of hereditary cancers: in the colon-rectum multiple tumors represent 5-10% of all colorectal cancer cases. A portion of these cases belongs to hereditary non-polyposis colorectal cancer (HNPCC), a genetic cancer syndrome due to mismatch repair (MMR) gene mutations, phenotypically expressed as microsatellite instability (MSI); the majority of multiple tumors, however, is apparently without any family history. We analyzed 78 (38 synchronous and 40 metachronous) neoplasms from 37 patients with multiple tumors of the large bowel, both HNPCC and sporadic, with the aim of identifying a common genetic basis in multiple tumors. DNA was extracted from normal and cancerous formalin-fixed tissue and was analyzed for MSI using 6 markers. Tumors showing MSI in at least 2 of 6 microsatellite loci were defined as MSI(+). The overall number of MSI(+) tumors was 22 (28.2% of the total). A significant difference in the rate of MSI(+) between HNPCC and sporadic tumors was observed (85% vs. 17%). In the same patients, the MSI phenotype of synchronous tumors (both HNPCC and sporadic) tended to be more concordant than that of the metachronous ones. The higher frequency of MSI in HNPCC than in sporadic tumors, even when multiple, suggests that the involvement of MMR genes in the pathogenesis of the sporadic cases may be uncommon, thus confirming that screening for MSI in multiple colorectal tumors could be a useful tool in the identification of HNPCC in the general population.

Microsatellite instability in multiple colorectal tumors

Tumor multiplicity is a hallmark of hereditary cancers: in the colon-rectum multiple tumors represent 5-10% of all colorectal cancer cases. A portion of these cases belongs to hereditary non-polyposis colorectal cancer (HNPCC), a genetic cancer syndrome due to mismatch repair (MMR) gene mutations, phenotypically expressed as microsatellite instability (MSI); the majority of multiple tumors, however, is apparently without any family history. We analyzed 78 (38 synchronous and 40 metachronous) neoplasms from 37 patients with multiple tumors of the large bowel, both HNPCC and sporadic, with the aim of identifying a common genetic basis in multiple tumors. DNA was extracted from normal and cancerous formalin-fixed tissue and was analyzed for MSI using 6 markers. Tumors showing MSI in at least 2 of 6 microsatellite loci were defined as MSI(+). The overall number of MSI(+) tumors was 22 (28.2% of the total). A significant difference in the rate of MSI(+) between HNPCC and sporadic tumors was observed (85% vs. 17%). In the same patients, the MSI phenotype of synchronous tumors (both HNPCC and sporadic) tended to be more concordant than that of the metachronous ones. The higher frequency of MSI in HNPCC than in sporadic tumors, even when multiple, suggests that the involvement of MMR genes in the pathogenesis of the sporadic cases may be uncommon, thus confirming that screening for MSI in multiple colorectal tumors could be a useful tool in the identification of HNPCC in the general population.

Epidemiology of cancer of the large bowel--the 12-year experience of a specialized registry in northern Italy

BACKGROUND

In 1984, a specialized colorectal cancer registry was instituted in Modena; aims of the Registry were: the evaluation of incidence and mortality, the study of morphological aspects, staging, survival and familiarity of the registered patients.

AIMS

Purpose of the research was to provide an updated description of the main findings (in particular, incidence, staging, morphology and survival) observed in the 12-year registration period.

PATIENTS AND METHODS

Between January 1984 and December 1995, 1,899 malignancies of the large bowel in 1,831 patients were registered. Tumours were classified according to the International Classification of the Diseases for Oncology (ICDO) and staged with the TNM system. Cancer specific survival was assessed with life table analysis and Log-Rank tests.

RESULTS

Crude incidence rate showed minor fluctuations between 1984 and 1989, but tended to rise in the following years. Tumours were mostly located distal to the splenic flexure (73.3% of the total), with a slight tendency over time to a gradual "shift" to the right colon. Staging became progressively more favourable throughout the registration; in 1984 both stages I, II and stage IV + unstaged lesions represented 40% of the total, but in 1995 the former rose to 50% whereas the latter fell to 21.6% (p < 0.001). This move to earlier stages resulted in an improved survival of patients registered in 1990-91 versus 1984-85 (Log-Rank 14.3 p < 0.002). Factors associated with a poor survival were the advanced age of patients at diagnosis (> 74) and clinical stage.

Small bowel carcinoma in hereditary nonpolyposis colorectal cancer

A 53-yr-old man, a member of a hereditary nonpolyposis colorectal cancer (HNPCC) family, with previous colonoscopic polypectomies, presented for persisting vomiting and marked signs of dehydration. Previous radiological and endoscopic examinations of the upper digestive tract were negative, with the exception of the presence of a duodenal adenomatous polyp. Enteroclysis led to a diagnosis of obstruction at the Treitz angle due to a moderately differentiated adenocarcinoma. Microsatellite instability was demonstrated in the DNA extracted from the tumor. The patient was the carrier of a mutation in the intron 13 of the hMLH1 gene, one of the four mismatch repair genes known to be responsible for HNPCC.

Scanning electron microscopy of aberrant crypt foci in human colorectal mucosa

BACKGROUND

Aberrant crypt foci (ACF) are clusters of morphologically altered crypts which can be observed by light or stereomicroscopy on the mucosal surface of the colon after staining with methylene-blue. They probably represent one of the earliest events in human colorectal carcinogenesis. The main purpose of the present study was to observe the surface features of aberrant and normal colonic crypts in humans using scanning electron microscopy (SEM) in order to find and measure differences between aberrant and normal.

MATERIALS AND METHODS

Fifteen mucosal specimens containing ACF and 8 with normal mucosa taken from patients operated on for colon cancer were observed under a scanning electron microscope.

RESULTS

By SEM ACF were easily observed on the mucosal surface, because they showed a well defined border and were elevated on the mucosal surface. Under higher magnification luminal openings of aberrant crypts had a larger overall average diameter than normal (37.6 microns +/- 13.5, mean +/- SD, vs 15.9 microns +/- 4.9, P = 0.001), though when crypt multiplicity of ACF (number of crypts per ACF) was higher, the diameter of luminal openings tended to be smaller and similar to those of normal crypts, with weak negative correlation between crypt multiplicity of ACF and mean diameter of aberrant luminal openings (r = 0.27). Finally, the mucosal surface among aberrant crypts was flattened because of a loss of microvilli. in conclusion, scanning electron microscopy allows a better definition of the topological features of aberrant crypt foci than light or stereomicroscopy.

Frequency and type of colorectal tumors in asymptomatic high-risk individuals in families with hereditary nonpolyposis colorectal cancer

In hereditary nonpolyposis colorectal cancer (HNPCC, or Lynch syndrome) a close surveillance is usually proposed to high-risk family members with the ultimate goal of reducing cancer incidence and mortality. Through a specialized registry, between 1984 and 1996, we identified 31 families with clinical features of HNPCC. A total of 390 first-degree relatives of affected patients were considered at high risk for colorectal cancer. The main purposes of this study were: (a) to assess overall compliance; and (b) to evaluate the frequency and morphological features of tumors detected at endoscopy. Two hundred twenty-three subjects could be directly interviewed and colonoscopy strongly recommended. Each of the 86 individuals who underwent colonoscopy was matched to a control of the same age (+/-3 years) and sex (control subjects were seeking endoscopy for constipation, rectal bleeding or abdominal discomfort). Of the 390 individuals traced as "at risk," 223 (57.2%) could be contacted, and, of these, 86 (38.6%, or 22.0% of the total) underwent colonoscopy. One or more colorectal lesions were found in 35 of 86 (40.7%) HNPCC asymptomatic family members and in 15 (17.4%; P < 0.001) controls. In the former group, 29 adenomas were detected in 20 individuals as opposed to 11 adenomas in 9 subjects among controls (P < 0.03). Moreover, adenomas in family members were significantly larger [9.1 +/- 5.9 mm (mean +/- SD) versus 5.8 +/- 3.7 mm; P < 0.02] and more frequently showed a tubulovillous histological type and a high degree of dysplasia. Five colorectal carcinomas (in four patients) were detected among cases (four of which were located between the cecum and the hepatic flexure); only one was detected among controls. Surveillance of high-risk subjects in HNPCC families can be carried out only in a fraction of them, because the majority cannot be reached or refuse to collaborate. On the other hand, the frequency of newly detected lesions among family members and the possible aggressive behavior of the lesions render pancolonoscopy necessary at regular intervals of time.

Aberrant crypt foci in patients with colorectal cancer

Aberrant crypt foci (ACF) are clusters of abnormally large colonic crypts identified on the mucosal surface of the human colon. They are thought to be preneoplastic lesions. The aim of the present study was to compare density (number of ACF per square cm of mucosal surface), crypt multiplicity (number of crypts per ACF) and histology of ACF in colonic resections of colorectal cancer patients resident in two Italian provinces with a twofold difference in colorectal cancer incidence rates. Thirty-two and 26 colonic resections were collected after operation in Ragusa (Southern Italy) and Modena (Northern Italy), respectively, and fixed in 10% formalin. Mucosal layers were observed under a light microscope at 25x after staining with methylene blue. Density of ACF was significantly higher in Modena (median 0.101 ACF cm(-2)) than in Ragusa (0.049, P = 0.001), whereas there was no difference in crypt multiplicity. ACF were classified into three groups according to histological features: ACF with mild alterations (hypertrophic ACF, 73%), ACF with hyperplasia (hyperplastic ACF, 17%) and ACF with dysplasia (microadenomas, 10%). The proportions of ACF in the three groups were similar in the two provinces. Density of ACF was higher and crypt multiplicity lower proceeding from proximal to distal large bowel. Microadenomas were observed only in the colon, whereas hyperplastic ACF were more frequent in the rectum. In conclusion, density of ACF correlates with colorectal cancer rates in two Italian provinces, and shows a positive gradient from proximal to distal large bowel. Histology of ACF suggests that they may be precursors of both hyperplastic and adenomatous polyps. These data provide further evidence of the role of ACF in human colorectal carcinogenesis.

MLH1 and MSH2 constitutional mutations in colorectal cancer families not meeting the standard criteria for hereditary nonpolyposis colorectal cancer

Genetic diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC) may have a significant impact on the clinical management of patients and their at-risk relatives. At present, clinical criteria represent the simplest and most useful method for the identification of HNPCC families and for the selection of candidates for genetic testing. However, reports of mismatch repair (MMR) gene mutations in families not fulfilling the minimal diagnostic criteria point out the necessity to identify additional clinical parameters suggestive of genetic predisposition to colorectal cancer (CRC) related to MMR defects. We thus investigated a series of 32 Italian putative HNPCC individuals selected on the basis of one of the following criteria: 1) family history of CRC and/or other extracolonic tumors; 2) early-onset CRC; and 3) presence of multiple primary malignancies in the same individual. These patients were investigated for the presence of MLH1 and MSH2 mutations by single-strand conformation polymorphism analysis. Pathogenetic truncating mutations were identified in 4 (12.5%) cases, 3 of them involving MSH2 and 1 MLH1. In addition, 2 missense MLH1 variants of uncertain significance were observed. All pathogenetic mutations were associated with early age (<40 years) at onset and proximal CRC location. Our results support the contention that constitutional MMR mutations can also occur in individuals without the classical HNPCC pattern. Moreover, evaluation of the clinical parameters associated with MMR mutations indicates that early onset combined with CRC location in the proximal colon can be definitely considered suggestive of MMR-related hereditary CRC and should be included among the guidelines for referring patients for genetic testing.

[Survival for tumors of the colon and the rectum in Italy]

In population based from four Italian cancer registries (Varese, Modena, Latina, Ragusa), five-years relative survival was 34% for colon cancer patients (no. = 1864) and 28% from rectum cancer patients (no. = 1117). However, rectum cancer patients showed higher survival rates in the first year of follow-up, which is possibly due to earlier diagnosis for sites more accessible to clinical examination. For colorectal cancer, age was an important prognostic factor, both in univariate and in multivariate analysis, adjusting for competitive mortality, sex, geographical area and year of diagnosis. In the same multivariate analysis, the prognosis was better for women, significantly for colon cancer and the excess death risk was reduced by 25-30% from 1978-79 to 1984-85. No significant differences were found among different geographical areas, possibly because of the low number of patients from some of the participating cancer registries.

Estimation and projections of colorectal cancer trends in Italy

BACKGROUND

Occurrence of and prognosis for tumours of the colon and rectum are thought to be changing rapidly due to simultaneous changes in risk factor prevalence, early diagnosis and treatment. In this paper time trends of morbidity, survival and mortality for colorectal cancer during the period 1970-1990 are estimated and analysed.

METHODS

Mortality trends were obtained from official death certificates. Relative survival rates were computed from population-based cancer registries. Incidence and prevalence rates were estimated from mortality and survival data.

RESULTS

Incidence rates were increasing during the period considered, with a lower rate of increase for the youngest birth cohorts. Relative survival rates of both colon and rectum cancers were higher for women, and for younger age groups, and were positively associated with period of diagnosis. No significant survival difference among the cancer registries used was found. A total of about 155,000 prevalent cases, 40% of which had been diagnosed > or = 7 years before, were estimated in the Italian population for the year 1990. Mortality rates were slightly increasing for men and stable for women. Projections of colorectal cancer trends to the year 2000 indicate major expected rises in both incidence and prevalence.

CONCLUSION

Colorectal cancer represents a problem of growing impact for health services in Italy. This conclusion can probably be extended to many developed countries.

Colorectal carcinoma in different age groups: a population-based investigation

Although colorectal cancer is a disease of the older population, these tumors are not infrequent before the age of 55. Through the data of a population-based registry, we proposed giving a description of the clinical features of three groups of patients in whom the disease occurred at a relatively early age of onset (group I: < 40 yr; group II: 41-50 yr; group III: 51-55 yr). There were only 14 patients under the age of 40 yr (1.1% of total registered patients, n = 1298 in the period 1984-1992). Group II and III represented 5.9% and 6.0%, respectively (n = 76 and 78), with minor fluctuations throughout the 9-yr period of registration. Inherited colorectal tumors [hereditary nonpolyposis colorectal cancer (HNPCC), adenomatosis coli, and suspected HNPCC] accounted for 38.4% of group I patients (5 of 14), 17.1% of group II, 10.2% of group III, and only 3.5% of individuals older than 55 (p, for trend, < 0.001). Thus, hereditary colorectal tumors were detected significantly more often in younger individuals. The majority of colorectal malignancies were localized in the left colon or rectum in all three groups, with a tendency (not significant) to a preferential localization in the right colon for tumors developed in group I (37% vs 18% and 14% in groups II and III, respectively). Pathological stage and main histological types did not differ among the three groups. Finally, life-table analysis did not show significant differences in 5-yr survival among the three groups; however, when considered together, early onset cases showed a more favorable prognosis than older individuals (log-rank 11.6; p < 0.001). In conclusion, colorectal cancer is diagnosed very rarely before the age of 40 yr, whereas about 12% of all cases belong to the age group 41 to 55 yr of age. Hereditary tumors were found more frequently in younger patients, with a well-defined inverse relationship between age of onset and frequency of genetically determined tumors. Finally, the clinical outcome was more favorable in the whole series of early onset cases than in older registered patients.

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

Previous survival studies suggested a better prognosis of hereditary nonpolyposis colorectal cancer (HNPCC) patients compared with the sporadic counterpart. In the present study we evaluated the clinical outcome of HNPCC patients with respect to that of patients with colorectal cancer recorded in a population-based cancer registry. We assessed survival of 85 colorectal cancer patients from 24 unrelated families defined as having HNPCC according to the criteria of the International Collaborative Group, for whom adequate information on subject- and tumor-related parameters and a 5-year follow-up (cancer diagnosis from 1980-1989) were available. Three hundred and seventy-seven colorectal cancer patients, registered from 1984-1986, with a 5-year follow-up, were used for comparison. Colorectal cancer-specific 5-year survival rates were 55.2% and 42.5% for HNPCC and non-HNPCC, respectively. Using Cox regression analysis, tumor staging and location were independently associated with survival, whereas HNPCC diagnosis was not. Stage II HNPCC cases exhibited a better prognosis than non-HNPCC patients. By Cox regression analysis, none of the variables were significantly related to survival. Both overall and stage II HNPCC cases showed a survival advantage in comparison with non-HNPCC patients. However, the difference disappeared when clinical and pathological variables were controlled for with a Cox regression analysis.

Histology of aberrant crypt foci in the human colon

Aberrant crypt foci (ACF) have been identified in the methylene-blue stained mucosa of the human colon. Some lines of evidence suggest that ACF may be precursors of colon cancer. The objective of the present study was to establish morphological criteria able to define and classify ACF in histological sections. Twenty-four colectomy specimens were collected after operation for colorectal cancer and fixed in 10% formalin. Strips of grossly normal mucosa were stained in a 0.2% solution of methylene blue in saline for 5-10 min. The strips were measured, put on a glass slide and observed under a light microscope at x25. One hundred and fourteen ACF identified by topology were sectioned parallel to the muscularis mucosae. Eighty-four ACF were evident at histological examination and could be classified into three main groups: group A (61 ACF, 72.6%) including foci whose epithelial cells had regular nuclei, with only mild or focal crowding but no stratification, no mucin depletion and no dysplasia; group B (16 ACF, 19.1%), in which features of hyperplasia were evident; and group C (seven ACF, 8.3%) including foci with enlarged, crowded and stratified nuclei, mucin depletion, frequent mitoses, and evident dysplasia, diffuse or focal (mild in five cases, moderate in two) representing microadenomas. Finally, hyperplastic foci were significantly larger than foci of group A and C. Group B ACF were also more frequent in the rectum than in the colon. In conclusion, selected histological features allow the definition of groups of ACF, which may represent sequential steps in the development of human colorectal tumours.

Characterization of MSH2 and MLH1 mutations in Italian families with hereditary nonpolyposis colorectal cancer

Mismatch repair genes MSH2 and MLH1 are considered to be the two major genes that are responsible for hereditary nonpolyposis colorectal cancer (HNPCC). Germline heterozygous inactivating mutations of MSH2 and MLH1 have been identified previously in a substantial fraction of individuals who are predisposed genetically to colorectal carcinoma (CRC) and other tumors of the HNPCC spectrum. With the aim of determining the relevance of these two genes in the Italian population, we submitted to mutational analysis a set of 17 HNPCC families, all of which fulfilled the "Amsterdam criteria." A combination of different techniques, including reverse transcription-polymerase chain reaction (RT-PCR) of long fragments and single-strand conformation polymorphism (SSCP) on cDNA and genomic DNA, allowed the identification of ten molecular variants, seven of which are predicted to inactivate mismatch repair function. The mutated predisposing gene was MSH2 in two families and MLH1 in five other families. All of the mutations were characterized by DNA sequencing and appeared to involve different molecular mechanisms, such as short in-frame and out-of-frame deletions, splicing errors, and nonsense mutations. This study also demonstrates that, in the Italian population, a considerable fraction of HNPCC families (at least 41%) is linked to MSH2 and MLH1 mutations.

A two-locus model for hereditary non-polyposis colorectal cancer in Modena, Italy

Complex segregation analysis was conducted in a series of patients with hereditary non-polyposis colorectal cancer (HNPCC) ascertained through probands registered in the Cancer Registry of the Health Care District of Modena, Northern Italy. Altogether there were 125 nuclear families segregating for HNPCC, for a total of 672 individuals. The analysis favoured a two-locus model, with both susceptibility genes rare and dominant. The gene frequency of the deleterious allele at the major locus is estimated to be low qm = 0.004 and for the second locus the estimate is even lower q = 0.00003. Both genes defining the two-locus model seem to be highly penetrant. The lifetime penetrance of the abnormal gene at the major locus is estimated to be 0.73 for female, while the estimation for male is higher, 0.85.

K-ras and p53 mutations in hereditary non-polyposis colorectal cancers

Genetic instability related to defective DNA mismatch repair genes may be involved in the pathogenesis of carcinoma in Hereditary Non-Polyposis Colorectal Cancer (HNPCC). To test that the targets of genetic instability could include critical transforming genes involved in colon tumor progression, we examined 23 colorectal carcinomas in patients with HNPCC in order to detect somatic mutations in K-ras and p53 genes. Using single strand conformation polymorphism followed by direct DNA sequencing, we detected 4 mutations in K-ras gene (17%) and 3 in p53 gene (13%) which change the amino acid sequence of the protein p53. This is significantly lower than in sporadic cancer. Our data suggest that colon cancer in HNPCC might partly involve a distinct pathogenetic mechanism that involves other genes than those altered in sporadic tumors.

Characterization of MSH2 and MLH1 mutations in Italian families with hereditary nonpolyposis colorectal cancer

Mismatch repair genes MSH2 and MLH1 are considered to be the two major genes that are responsible for hereditary nonpolyposis colorectal cancer (HNPCC). Germline heterozygous inactivating mutations of MSH2 and MLH1 have been identified previously in a substantial fraction of individuals who are predisposed genetically to colorectal carcinoma (CRC) and other tumors of the HNPCC spectrum. With the aim of determining the relevance of these two genes in the Italian population, we submitted to mutational analysis a set of 17 HNPCC families, all of which fulfilled the "Amsterdam criteria." A combination of different techniques, including reverse transcription-polymerase chain reaction (RT-PCR) of long fragments and single-strand conformation polymorphism (SSCP) on cDNA and genomic DNA, allowed the identification of ten molecular variants, seven of which are predicted to inactivate mismatch repair function. The mutated predisposing gene was MSH2 in two families and MLH1 in five other families. All of the mutations were characterized by DNA sequencing and appeared to involve different molecular mechanisms, such as short in-frame and out-of-frame deletions, splicing errors, and nonsense mutations. This study also demonstrates that, in the Italian population, a considerable fraction of HNPCC families (at least 41%) is linked to MSH2 and MLH1 mutations.

Chemoprevention of colorectal tumors: role of lactulose and of other agents

Chemoprevention can be defined as an attempt at cancer control in which the occurrence of the disease is prevented by the administration of one (or more) chemical compounds. Main problems in chemoprevention studies are the choice of a suitable drug, the choice of an appropriate intermediate or definitive end point, and the definition of the population which should be investigated. Main classes of chemopreventive agents include vitamins, non-steroid antinflammatory drugs, minerals such as calcium or selenium, and other antioxidants such as N-acetylcysteine. Chemoprevention is particularly appealing in colorectal cancer, either because these lesions develop through a multistep process, or owing to the concept of "field carcinogenesis'. Between 1985 and 1990 we carried out a controlled study in which antioxidant vitamins or lactulose were used in an attempt to prevent the recurrence of colorectal polyps after their endoscopic removal. Among the 209 patients who could be evaluated, polyps recurred in 5.7% of the individuals who were given vitamins (A, C and E), 14.7% of patients given lactulose and 35.9% of untreated controls (chi 2 = 17.1, P < 0.001). The study suggested that either antioxidant vitamins or lactulose could be effective in reducing the recurrence rate of adenomatous polyps. In a subsequent on-going study, lower doses of the same vitamins were tested versus N-acetylcysteine (600 mg/day) or no treatment. Preliminary results showed a 40% reduction of the recurrence of polyps (versus controls) in individuals given N-acetylcysteine, while the effect of lower doses of vitamins was less appreciable. Definitive results of the study should be available by the end of 1998.

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.

K-ras and p53 mutations in human colorectal aberrant crypt foci

Aberrant crypt foci (ACF) are putative precursor lesions of colon cancer, recently identified on the methylene blue-stained mucosal surface of human colon. No mutations in K-ras or p53 genes were found by non-radioactive single-strand conformation polymorphism analysis in 14 ACF collected from five patients. Using the more sensitive method of allele-specific polymerase chain reaction (PCR) for K-ras, 8 of 14 ACF were found to contain K-ras mutations, suggesting that mutated cells are present in minute clones in ACF. No dysplasia was observed in any of the ACF containing a mutated clone. The presence of K-ras mutations in ACF suggests that these lesions occur at a very early stage in human colorectal carcinogenesis.