Ophiolitic outcrops, naturally occurring asbestos exposure and mortality risk from malignant mesothelioma in Calabria (Southern Italy).

OBJECTIVES: Naturally occurring asbestos from ophiolitic outcrops can pose a health risk to the resident population. Some studies have documented this risk of exposure in many areas around the world. The aim of the study is to estimate the possible impact on health caused by asbestos outcrops present in some areas of Calabria, a region of southern Italy. STUDY DESIGN: The design of the study is observational and uses routinely collected data on employment, compensations and mortality. METHODS: Data from archives of mortality in the period 2005-2015 were selected. Standardized mortality ratio (SMR) for malignant mesothelioma (MM) by municipalities of residence with reference to the regional population was estimated assuming a Poisson distribution of the data. Administrative archives of companies' employment records and occupational disease compensation data were used to exclude occupational origin cases. RESULTS: A total of 163 cases of MM were identified. Statistically significant excess risks (P-value <0.05) were observed for several municipalities, some of which were located in areas where asbestos outcrops had previously been identified. Significant SMRs vary between 44.0 and 5.2. The mean age at death in the areas at risk of ophiolitic outcrops ranges from 65.4 to 77.1 years, and the gender ratio (male/female) ranges from 0.66 to 1.3. CONCLUSIONS: Monitoring of areas most involved in the risk of environmental contamination from ophiolitic outcrops is highly suggested. Full implementation of the local MM surveillance system is strongly encouraged. Further investigations are recommended to specifically identify the cause of exposure and confirm the hypothesis of a causal association with asbestos naturally occurring in these risk areas.

[The contribution of surveillance systems of occupational diseases and mesothelioma in environmental health studies]. / Il contributo dei sistemi di registrazione delle malattie professionali e dei mesoteliomi negli studi su ambiente e salute.

National surveillance systems of occupational diseases may contribute to evaluate the work-related component of diseases investigated in SENTIERI Project. For a description of SENTIERI, refer to the 2010 Supplement of Epidemiology & Prevention devoted to SENTIERI Project. The National Workers Compensation Authority (INAIL) archives all occupational diseases claims (more than 230 000 in the period 2000-2007) and is in charge of their compensation. The Italian National Mesothelioma Register (ReNaM) and the Sinonasal Cancer Register (ReNaTuNS) record high occupational etiological fraction neoplasms (i.e. mesothelioma and sinonasal cancers). The former has identified more than 10 000 mesothelioma cases until now, and covers almost the whole country; the latter is active only in three Italian regions, Piemonte, Lombardia and Toscana. The monitoring of cancer sites at lower occupational etiological fraction is based on a record-linkage procedure between population-based cancer registries and employment history data, available at the Italian National Institute for Social Security (INPS). Finally, the informative system Mal.Prof collects and classifies all the diseases possibly related to the work environment reported by the Prevention Services of the Local Health Units.

Industry and job-specific mortality after occupational exposure to silica dust.

BACKGROUND: Occupational exposure to silica dust occurs in many workplaces and is well known to cause silicosis. However, the link between silica exposure, silicosis and other diseases is still disputed. AIMS: To evaluate cause-specific mortality in a cohort of Italian silicotics. METHODS: The cohort included 2034 male compensated for silicosis between 1943 and 1986, alive on 1 January 1987 and resident in the Latium region (Italy). Mortality follow-up was from 1987 to 2006. Vital status and death causes were ascertained from the regional mortality archive. Standardized mortality ratios (SMRs) were computed assuming a Poisson distribution of observed deaths. RESULTS: Significant excess mortality was observed from all causes (SMR: 1.17, 95% CI: 1.11-1.24), cancer of trachea, bronchus and lung (SMR: 1.39, 95% CI: 1.17-1.64), cancer of larynx (SMR: 2.18, 95% CI: 1.32-3.60) and tuberculosis (SMR: 5.85, 95% CI: 3.03-11.30). Higher risks were observed for masons (lung cancer, SMR: 2.46, 95% CI: 1.65-3.66) and miners (larynx cancer, SMR: 5.31, 95% CI: 1.88-15.03). In a Poisson regression analysis, the relative risk of death from lung cancer and silicosis increased with silicosis severity and decreased in more recent compensation periods. CONCLUSIONS: The excess mortality from respiratory tract cancers and other diseases detected among Italian workers compensated for silicosis confirms previous epidemiological findings.

[The surveillance of occupational risks. Problems and perspectives of the recent legislative framework after the national preliminary survey]. / I dati sanitari aggregati e di rischio dei lavoratori sottoposti a sorveglianza sanitaria. Risultati preliminari dello studio pilota nazionale sulle comunicazioni ex art. 40. D.lgs 81/2008.

BACKGROUND: Legislation in Italy concerning health, safety and prevention at the workplace recently established a new data communication standard OBJECTIVES: The findings are reported of a specific survey on 18 Local Health Units (ASL) over the entire Italian territory, aimed at identifying the critical points in data management and analyze the available information. METHODS: The occupational health physician for each company must collect and transmit information on the number of workers submitted to health surveillance protocols to the Local Health Unit. Information must be divided by risk factor and gender Local health Units then transmit the data to the Regions and finally to the Italian National Institute for Occupational Safety and Prevention (ISPESL). RESULTS: A sample of 22.977 companies was studied, providing information on about 410,009 workers undergoing health surveillance protocols. Carrying or moving heavy loads, exposure to noise, VDU and chemical substances were the most frequent risk factors. The difference between genders was significant in risk allocation, with exposures to VDU and biological agents prevalently among females. CONCLUSIONS: The information thus collected suffered from a lack of data organization and completeness in the sample under study, but nevertheless provides preliminary evidence of a map of occupational risks on a national basis, confirming the potential for the new law (D.Lgs 81/2008) to investigate health safety and prevention at the workplace.

[The register of exposed workers to carcinogens: legislative framework and data analysis]. / Il registro dei lavoratori esposti ad agenti cancerogeni: quadro legislative e analisi dei dati.

BACKGROUND: On the basis of the law which introduced the registration of occupational exposures to carcinogens (Legislative Decree 626/94), the National Institute for Occupational Safety and Prevention designed and implemented an information system for collecting and recording such information. The Ministry of Health Decree No 155/2007, which established the procedures for record keeping and transmission of registers of exposed workers, regulated the legislative fJamework in this field. OBJECTIVES: The aim of the study was to illustrate some of the major legislative issues and toprovide summary statistics, after one year of entry into force of this Decree. METHODS: The main information to record is: the carcinogenic agents used, the type of occupational exposure and data on the environmental measurements. Descriptive statistical analysis were carried out, by sector of economic activity, carcinogen agent and worker's occupation. RESULTS: As at 31 December 2008 the information recorded, altogether, covered: 6000 firms, 79,000 workers, 164,000 exposures and 100,000 measurements. Most of the exposures occurred in the manufacturing and construction industries and in commercial activities. CONCLUSIONS: Such surveillance system, established as a result of the institution of exposure registers, makes it possible to plan analytical studies, both for monitoring the effects of exposure, even at low doses, and for assessing the prevention and protection measures. It is hoped that the recent readjustment law (Legislative Decree 81/2008) will promote awareness of all subjects involved in the recording procedures (employers, physicians, local health units, research institutes, etc.), thus increasing the quality and coverage of data transmission.

Magnitude of asbestos-related lung cancer mortality in Italy.

An ecological study, based on a data set containing all lung and pleural cancer deaths in each Italian municipality in the period 1980-2001, was performed. The pleural to lung cancer ratio was estimated to be 1 : 1 and 3% (around 700) of all male lung cancer deaths were found to be asbestos-related.

[In-progress matrix for occupational cancer recognition]. / Matrice "inprogress" per la consultazione dei dati bibliografici relativi alle neoplasie di sospetta origine professionale.

BACKGROUND: In Italy only a small proportion of all cancers is reported to the national labour insurance board and recognized as having an occupational origin. Cancers with a lower etiological fraction such as lung or bladder cancer have a lower rate of recognition than mesotheliomas or sino-nasal tumours either because of a lack of information obtained via specific occupational anamnesis or because knowledge concerning occupational carcinogens is still uncertain. OBJECTIVES: To interpret findings and advance new working hypotheses, within the framework of an occupational monitoring survey project (OCCAM) we performed an extensive bibliographical search in the scientific literature on occupational cancer. METHODS AND RESULTS: We built an on-line "literature matrix" (www.occam.it) containing positive" results from 685 cohort, case-control and cross-sectional epidemiological studies on occupational cancer, from which 1870 citations were obtained describing risk increases by type of cancer and industry. Production cycles or type of industry (iron foundry, leather and shoe manufacturing, etc.) constitute one axis of the matrix and the other consists of type of cancer by site. CONCLUSIONS: This tool is not only useful for interpretation of evidence arising from occupational cancer surveys but was also intended to be a fast and easy-to-use working tool for occupational physicians, general practitioners and many other specialists to investigate and ascertain the possible occupational origin of a cancer case.

Occupational exposure levels to wood dust in Italy, 1996-2006.

BACKGROUND: Wood dust has been classified as carcinogenic to humans and the association with nasal cancer risk has been observed in a large number of epidemiological studies. OBJECTIVES: The aim of this study is to summarise data about occupational exposure levels to wood dust in Italy and to examine some exposure determinants. METHODS: Exposure measurements on wood dust were extracted from the SIREP (Italian Information System on Occupational Exposure to Carcinogens) database between 1996-2006. Descriptive statistics were calculated for exposure-related variables using univariate analyses. The prevalence of elevated exposure levels was estimated overall and for some industrial sectors. A multifactorial analysis of variance was performed to determine which factors influenced exposure levels to wood dust. RESULTS: The total number of exposure measurements (n) reported is 10,837, which refer to 10,528 workers and 1181 companies. The overall arithmetic mean is 1.44 mg/m(3) and the geometric mean is 0.97 mg/m(3). Industrial sectors at high risk are "manufacture of wood and wood products" (n = 5539) as well as "manufacture of furniture" (n = 4347). About 74% of exposure measurements report a value <2 mg/m(3). In the multifactorial analysis, it has been found that job category, industrial sector, company size and geographical location of the company influence the exposure levels. CONCLUSIONS: This study confirms the previous findings about occupational exposure to wood dust (mainly in wood industry and among woodworking machine operators) and suggests further investigations on other risk sectors (building and repairing of ships and boats). The potential of the occupational exposure database as a source of data for exposure assessment and surveillance is also confirmed.

Frequency of constitutional MSH6 mutations in a consecutive series of families with clinical suspicion of HNPCC.

A large majority of constitutional mutations in hereditary non-polyposis colorectal cancer (HNPCC) are because of the MHL 1 or MSH 2 genes. In a lower fraction of cases, another gene of the mismatch repair (MMR) machinery, MSH6, may be responsible. Families with MSH6 mutations are difficult to recognize, as microsatellite instability (MSI) may not be detectable and immunohistochemistry (IHC) may give ambiguous results. In the present study, we proposed (i) to determine the frequency of MSH6 mutations in a selected population of colorectal cancer patients obtained from a tumor registry, (ii) to assess whether IHC is a suitable tool for selecting and identifying MSH6 mutation carriers. One hundred neoplasms of the large bowel from suspected HNPCC families were analyzed for MSI (BAT 25 and BAT 26 markers) and immunohistochemical expression of the MSH6 protein. We found on 12 tumors (from different families) showing instability or lack of MSH6 expression. Among these, four potentially pathogenic MSH6 mutations were detected (del A at 2984; del TT at 3119; del AGG cod 385; and del CGT cod 1242) by direct gene sequencing. These represented 12.9% of all families with constitutional mutations of the DNA MMR genes. Thus, some 5% of all HNPCC families are featured by constitutional mutation of the MSH6 gene. This appears, however, as a minimum estimate; routine use of IHC and the study of large numbers of individuals and families with little or no evidence of Lynch syndrome might reveal that mutation of this gene account for a large fraction of HNPCC.

A mononucleotide markers panel to identify hMLH1/hMSH2 germline mutations.

Hereditary NonPolyposis Colorectal Cancer (Lynch syndrome) is an autosomal dominant disease caused by germline mutations in a class of genes deputed to maintain genomic integrity during cell replication, mutations result in a generalized genomic instability, particularly evident at microsatellite loci (Microsatellite Instability, MSI). MSI is present in 85-90% of colorectal cancers that occur in Lynch Syndrome. To standardize the molecular diagnosis of MSI, a panel of 5 microsatellite markers was proposed (known as the "Bethesda panel"). Aim of our study is to evaluate if MSI testing with two mononucleotide markers, such as BAT25 and BAT26, was sufficient to identify patients with hMLH1/hMSH2 germline mutations. We tested 105 tumours for MSI using both the Bethesda markers and the two mononucleotide markers BAT25 and BAT26. Moreover, immunohistochemical evaluation of MLH1 and MSH2 proteins was executed on the tumours with at least one unstable microsatellite, whereas germline hMLH1/hMSH2 mutations were searched for all cases showing two or more unstable microsatellites. The Bethesda panel detected more MSI(+) tumors than the mononucleotide panel (49.5% and 28.6%, respectively). However, the mononucleotide panel was more efficient to detect MSI(+) tumours with lack of expression of Mismatch Repair proteins (93% vs 54%). Germline mutations were detected in almost all patients whose tumours showed MSI and no expression of MLH1/MSH2 proteins. No germline mutations were found in patients with MSI(+) tumour defined only through dinucleotide markers. In conclusion, the proposed mononucleotide markers panel seems to have a higher predictive value to identify hMLH1 and hMSH2 mutation-positive patients with Lynch syndrome. Moreover, this panel showed increased specificity, thus improving the cost/effectiveness ratio of the biomolecular analyses.

[Malignant pleural cancers mortality and compensated cases for asbestos related diseases in Lazio municipalities (1980-2001)]. / Mortalità per tumore maligno della pleura e casi indennizzati di malattie asbesto correlate nei comuni del Lazio (1980-2001).

BACKGROUND: Occupational exposure to asbestos has been widely reported in the Region, but a high risk for non-occupational and environmental contaminations have also been documented. OBJECTIVES: To describe the geographical distribution ofpleural cancer deaths and compensated asbestosis cases from 1980 to 2001 in the Lazio Region. METHODS: For each municipality Standardized Mortality Ratios (SMRs) for pleural cancer and Standardized Incidence Ratios (SIRs) for asbestosis were estimated. Expected cases were estimated from age and gender specific rates in Lazio. SatScan software was used to identify clusters and to verf;j their statistical significance. RESULTS: 789 deaths from pleural cancer (495 males and 294 females) occurred in Lazio from 1980 to 2001. The standardized mortality rate per 100.000 inhabitants is 0,74 (0,95 for males and 0,54 for females). The main excess mortality from pleural cancer occurred in the municipalities of Civitavecchia (SMR: 269,9; 95% CI: 164,9 - 416,8), Colleferro (SMR: 304,9; 95% CI: 139,4-578,8) and Rocca Priora (SMR: 379,2; 95% CI: 103,3-970,9). Significant SIRs for compensated asbestosis cases were found in the industrial areas of the Naples-Rome highway and in the shipyard area of Civitavecchia. Nofemale compensated cases were found. The most important clusters were identified in the municipality of Civitavecchia for pleural cancer (p-value = 0,117) and in the Colleferro industrial area for compensated asbestosis cases (p-value = 0,001). CONCLUSIONS: Epidemiological surveillance of incident cases of malignant mesothelioma in the Lazio Region and the investigation of modalities of asbestos exposure are urgently needed for prevention of occupational diseases.

National epidemiologic surveillance systems of asbestos-related disease and the exposed workers register.

INTRODUCTION: Italy was the main European producer of asbestos for most of the 20th century and raw asbestos imports wee also significant until the 1990's; there was a mean delay of about ten years in the pattern of asbestos consumption in Italy compared with the USA, Australia, UK and Scandinavian countries. METHODS: A national surveillance system (ReNaM) was implemented to identify cases of mesothelioma and investigate the modalities of asbestos exposure. A register of exposed workers and a database of companies presumably involved in the asbestos exposure problem was also developed. ReNaM has a regional structure and an operative centres (COR) have been established in 16 Italian regions. RESULTS: The ReNaM database currently contains more than 5,000 mesothelioma cases and for 3,500 of these exposure modalities have been defined. Cases of pleural mesothelioma represent 93% of the total but there were also 334 cases of peritoneal mesothelioma, 15 of the pericardium and 14 of the tunica vaginalis of the testicle. Cases with ascertained exposure are thus distributed: 67.4% occupational exposure (ascertained, probable, possible), 4.3% domestic, 4.2% environmental and 1.3% hobby-related exposure, totalling 77.2%; 22.8% had unlikely or unknown exposure. The latency period is very long: on average 43.6 years. The register of asbestos-exposed workers contains figures on exposed workers notified to ISPESL up to 2004 and refers to the exposure period 1993-2003. The data registered cover 160 firms and about 700 workers. CONCLUSIONS: A national, coordinated and uniform epidemiological surveillance system of cases of mesothelioma and the definition of asbestos exposure through active research is extremely important in identifying unexpected contaminating sources. The register of asbestos-exposed workers allows risk to be monitored and protection measures to be implemented.

Retrospective mortality cohort study of Italian workers compensated for silicosis.

OBJECTIVES: To estimate cause specific mortality in a large cohort of Italian workers compensated for silicosis. METHODS: The cohort included 14 929 subjects (14,098 men and 831 women) compensated for silicosis between 1946 and 1979, alive on 1 January 1980, and resident in Tuscany (a region of central Italy with 3,547,000 inhabitants). Mortality follow up ranged from 1980 to 1999. Vital status and the causes of death were determined by linkage with the regional mortality registry and with the national mortality database. The cohort mortality rates were compared to the rates of the local reference population. SMRs and their 95% confidence intervals were computed assuming a Poisson distribution of the observed deaths. Specific SMR analyses were performed according to the level of disability, the year of compensation assignment, and the job type. RESULTS: A significant excess mortality was observed in male silicotics for cancer of the lung, trachea, and bronchus and cancer of the liver, respiratory diseases (silicosis, asbestosis, antracosilicosis, and other pneumoconiosis), and for tubercolosis. Statistically significant mortality excess was observed in female silicotics for respiratory diseases (specifically silicosis and other pneumoconiosis) and tuberculosis. Analyses for period of compensation assignment showed a twofold increased SMR for biliary tract cancer among female workers and for liver cancer among male workers compensated before 1970. CONCLUSIONS: The excess mortality from respiratory tract cancers and respiratory tract diseases detected in Italian compensated silicotics are in agreement with previous epidemiological studies. Although the twofold increased risk for liver cancer among males is suggestive of a possible association with silica dust exposure, the finding needs to be confirmed.

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.

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.

[Registry of the Italian Institute for Occupational Prevention and Safety of local productive units: methodology and structure]. / L'anagrafe ISPESL delle unità locali produttive: metodologia e struttura.

The Italian Institute for Occupational Prevention and Safety (ISPESL) carried out a register of enterprises operating in industry, services and agriculture sector to provide information on their location, economical activity and occupational data. This database has been built merging administrative files from the National Institute of Social Security (INPS) and the Computer Science Society of Italian Chambers of Commerce (InfoCamere). Enterprises have been classified by economic sector - in accordance with ISTAT (National Statistics Institute) "Ateco91" classification--and by accuracy level of the record linkage. In details, three different subsystems have been set up: (A) enterprises satisfying linkage; (B) enterprises in InfoCamere file not linked with INPS file; (C) enterprises in INPS file not linked with InfoCamere file. In the whole, 6.026.676 factories have been collected, of which 1.188.784 in group A, 4.543.091 in group B and 294.801 in group C. Establishing a database of information on industries may be useful to improve preventive programs and to plan health care surveillance systems.

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.

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.

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.