Cancer risk and the complexity of the interactions between environmental and host factors: HENVINET interactive diagrams as simple tools for exploring and understanding the scientific evidence.

BACKGROUND: Development of graphical/visual presentations of cancer etiology caused by environmental stressors is a process that requires combining the complex biological interactions between xenobiotics in living and occupational environment with genes (gene-environment interaction) and genomic and non-genomic based disease specific mechanisms in living organisms. Traditionally, presentation of causal relationships includes the statistical association between exposure to one xenobiotic and the disease corrected for the effect of potential confounders. METHODS: Within the FP6 project HENVINET, we aimed at considering together all known agents and mechanisms involved in development of selected cancer types. Selection of cancer types for causal diagrams was based on the corpus of available data and reported relative risk (RR). In constructing causal diagrams the complexity of the interactions between xenobiotics was considered a priority in the interpretation of cancer risk. Additionally, gene-environment interactions were incorporated such as polymorphisms in genes for repair and for phase I and II enzymes involved in metabolism of xenobiotics and their elimination. Information on possible age or gender susceptibility is also included. Diagrams are user friendly thanks to multistep access to information packages and the possibility of referring to related literature and a glossary of terms. Diagrams cover both chemical and physical agents (ionizing and non-ionizing radiation) and provide basic information on the strength of the association between type of exposure and cancer risk reported by human studies and supported by mechanistic studies. Causal diagrams developed within HENVINET project represent a valuable source of information for professionals working in the field of environmental health and epidemiology, and as educational material for students. INTRODUCTION: Cancer risk results from a complex interaction of environmental exposures with inherited gene polymorphisms, genetic burden collected during development and non genomic capacity of response to environmental insults. In order to adopt effective preventive measures and the associated regulatory actions, a comprehensive investigation of cancer etiology is crucial. Variations and fluctuations of cancer incidence in human populations do not necessarily reflect environmental pollution policies or population distribution of polymorphisms of genes known to be associated with increased cancer risk. Tools which may be used in such a comprehensive research, including molecular biology applied to field studies, require a methodological shift from the reductionism that has been used until recently as a basic axiom in interpretation of data. The complexity of the interactions between cells, genes and the environment, i.e. the resonance of the living matter with the environment, can be synthesized by systems biology. Within the HENVINET project such philosophy was followed in order to develop interactive causal diagrams for the investigation of cancers with possible etiology in environmental exposure. RESULTS: Causal diagrams represent integrated knowledge and seed tool for their future development and development of similar diagrams for other environmentally related diseases such as asthma or sterility. In this paper development and application of causal diagrams for cancer are presented and discussed.

Duration of exposure to environmental carcinogens affects DNA-adduct level in human lymphocytes.

BACKGROUND AND OBJECTIVE: An important issue in human biomonitoring is determining how exposure duration affects the kinetics of molecular biomarkers. In this study we compare the influence of exposure variables on DNA adducts. METHODS: DNA adducts were analysed by 32P-postlabelling in lympho/monocytes of 677 Caucasian subjects. RESULTS: After correction for other variables, DNA adducts increased depending on the length of occupational and smoke exposures. Higher DNA adducts were detected in workers with more than 14 years of exposure than in workers with shorter exposures (RR = 1.19, p = 0.049) and in smokers with more than 10 years of exposure than in smokers with shorter exposure (RR = 1.21, p <0.001). CONCLUSIONS: Exposure length is the primary factor affecting DNA-adduct level in lympho/monocytes both in smokers and in occupationally exposed subjects.

Predictive and prognostic significance of neuron-specific enolase (NSE) in non-small cell lung cancer.

BACKGROUND: The predictive and prognostic role of neuron-specific enolase (NSE) in non-small cell lung cancer (NSCLC) is still under debate. PATIENTS AND METHODS: To study these aspects, serum NSE was prospectively measured at baseline of first-line chemotherapy treatment and tested for correlation with clinical outcome in 129 advanced NSCLC patients. RESULTS: An objective response was achieved in 27 out of 65 (41.5%) patients with NSE < 8.6 ng/ml and in 38 out of 64 (59.4%) patients with NSE > or = 8.6 ng/ml (p = 0.05). Logistic analysis confirmed the positive association between objective response and NSE values > or = 8.6 ng/ml (odds ratio = 1.69; 95% confidence interval: 1.09-2.63; p = 0.02). Overall median survival was 10.8 months. A statistically significant prognostic effect on survival was found for performance status, stage and response to treatment, but not for baseline NSE value. CONCLUSION: Based on these data, baseline circulating tumor NSE levels appear to have a weak predictive role, but not a prognostic significance in patients with advanced NSCLC submitted to standard chemotherapy.

Genetic susceptibility to malignant mesothelioma and exposure to asbestos: the influence of the familial factor.

BACKGROUND: Asbestos is the principal etiological factor of malignant mesothelioma (MM), accounting for more than 80% of all tumor cases. However, other co-factors, including genetic susceptibility may play a role in the etiology of this disease, possibly modulating the effects of exposure to asbestos and other carcinogenic mineral fibers. The frequent report of familial clustering was the first indication supporting the involvement of genetic factors. Therefore, we performed an extensive literature search to evaluate existing studies reporting familial cases of MM. METHODS: Published reports addressing the issue of familial susceptibility to MM have been searched through PubMed using keywords and free text tools. Eighty-two citations were retrieved and 20 of them actually reported a familial cluster of MM. Three more articles were identified through the references. The probability that the observed familial clusters of mesothelioma could have randomly occurred in exposed families was evaluated with the Family History Score Zi (FHSi). RESULTS: The result of this analysis suggested that clustering of MM cases in families exposed to asbestos may be explained with the additional contribution of other familial factors. The FHSi allowed to reject the hypothesis of random occurrence of these clusters with a probability of a first type error ranging between 1 per cent and 1 per billion. CONCLUSIONS: The evaluation of the published materials supports the hypothesis that - although familial clustering of MM is largely attributable to shared asbestos exposure - the additional contribution of factors dealing with genetic susceptibility may play a role in the etiology of MM.

A randomized prospective comparison of self-expandable plastic stents and partially covered self-expandable metal stents in the palliation of malignant esophageal dysphagia.

OBJECTIVES: Self-expanding metal stents (SEMS) provide effective palliation in patients with malignant dysphagia, although severe complications and mortality may result. We performed a prospective controlled trial to compare a new self-expanding polyester mesh stent (Polyflex) with SEMS (Ultraflex). METHODS: One hundred one patients with unresectable esophageal carcinoma were randomized to placement of a Polyflex (N=47) or a partially covered Ultraflex (N=54) stent. Patients with esophagogastric junction (EGJ) malignancy were excluded. RESULTS: Placement was successful in 46 (98%) patients with the Polyflex and 54 (100%) patients with the Ultraflex stent. In one patient, the Polyflex stent could not be placed. After 1 wk, dysphagia was improved by at least 1 grade in 100% of the Polyflex group and in 94% of the Ultraflex group. Major complications were observed in 48% of the Polyflex group and 33% of the Ultraflex group. Intraprocedural perforation occurred in 1 Polyflex and 1 Ultraflex patient. Two Polyflex patients had postprocedural hemorrhage. Twenty (44%) patients with a Polyflex stent and 18 (33%) with an Ultraflex stent had recurrent dysphagia because of tumor overgrowth, stent migration, hyperplastic granulomatous reaction, or food bolus impaction. Multivariate analysis showed a significantly higher complication rate with Polyflex than with Ultraflex stents (odds ratio 2.3, 95% CI 1.2-4.4). However, median survival was 134 days with Polyflex and 122 days with Ultraflex stents (P=NS). CONCLUSIONS: No difference was seen in palliation of dysphagia between the two stents. Significantly more complications, especially late stent migration, were observed in the Polyflex group.

Clinical significance of serum mesothelin in patients with mesothelioma and lung cancer.

PURPOSE: High levels of serum-soluble mesothelin family proteins (SMRP) have been found to be associated with malignant mesothelioma (MM), but not lung cancer (LC). To verify the clinical role of this marker for both these tumors, we tested serum SMRP in the largest population of thoracic cancers ever assembled. EXPERIMENTAL DESIGN: SMRP blood concentrations were measured in 107 patients with MM, 215 patients with LC, 130 patients with benign respiratory diseases (BRD), and 262 controls. Statistical comparison between mean serum SMRP levels in all groups was done and receiver operating characteristic curves were constructed to evaluate the performance of this marker. RESULTS: SMRP levels were significantly higher in patients with MM and LC than in patients with benign respiratory diseases and controls (P < 0.001). The area under the receiver operating characteristic curve for serum SMRP discriminating MM and controls was 0.77 (95% confidence interval, 0.71-0.83), with a best cutoff of 1.00 nmol/L (sensitivity, 68.2%; specificity, 80.5%). In both MM and LC, serum SMRP levels did not differ significantly between early and late stages. High SMRP levels proved to be an independent negative prognostic factor in patients with MM. CONCLUSIONS: Our data confirm that serum SMRP is a promising marker for the diagnosis, prognosis, and clinical monitoring of MM. We found that serum SMRP dosage may prove helpful in LC diagnosis as well. These data may also have positive repercussions on secondary preventive medical strategies for workers previously exposed to asbestos.

The role of chromoendoscopy in the surveillance of the duodenum of patients with familial adenomatous polyposis.

Adenomas of the duodenum have been described in patients with familial adenomatous polyposis (FAP). Patients with FAP are at high risk for the development of periampullary cancer. The aim of our study was to evaluate if endoscopic visualization of small polyps, often overlooked at standard endoscopic examination, was improved by chromoendoscopy. Ten patients with FAP and previous colectomy underwent upper gastrointestinal endoscopy. Two skilled endoscopists were involved for each endoscopy. Evaluation of number and diameter of polyps was made before and after staining. After staining we detected a larger number of duodenal polyps than found at the standard endoscopic examination, the difference being statistically significant. This result seems to suggest that chromoendoscopy may improve diagnostic yield of endoscopy. Further studies are needed to suggest the best surveillance program and the appropriate therapeutic modality for these patients.

A modified self-expanding Niti-S stent for the management of benign hypopharyngeal strictures.

BACKGROUND: The management of patients with refractory hypopharyngeal strictures after surgery in combination with radiation therapy is disappointing, and nutrition through feeding tubes is often required. OBJECTIVE: To evaluate the efficacy and safety of a modified self-expanding Niti-S metal stent in the treatment of hypopharyngeal strictures after combined therapy for laryngeal cancer. DESIGN: Case series. SETTING: A general hospital and a university hospital. PATIENTS: Seven consecutive patients were included. One of them did not have laryngectomy. INTERVENTIONS: All patients received a modified Niti-S stent. MAIN OUTCOME MEASUREMENTS: Improvement of dysphagia, avoiding periodic bougienage, and enteral nutrition through feeding tubes. RESULTS: After placement of the first stent, dysphagia improved in all patients. Six of 7 patients developed stent migration and/or granulomatous tissue ingrowth or overgrowth. Additional stents were placed in all patients after a median of 3 months after the previous stent placement. One patient developed an esophagorespiratory fistula caused by a Polyflex stent. Two patients died of causes unrelated to the stent. The remaining 5 patients remained alive and asymptomatic after a median follow-up of 10 months. LIMITATIONS: Periodic stent exchange. Stent placement did not resolve the stricture definitively. We had a limited number of patients and have no long-term outcome data yet. CONCLUSIONS: The use of this modified Niti-S stent avoids both enteral nutrition through feeding tubes and the need for periodic bougienage in patients with difficult-to-treat benign hypopharyngeal strictures.

Polymorphisms of glutathione-S-transferase M1 and manganese superoxide dismutase are associated with the risk of malignant pleural mesothelioma.

Individual response to oxidative stress, due to exposure to asbestos fibres plays a significant role in the malignant pleural mesothelioma (MPM) etiology. The differential impact on MPM risk of polymorphic alleles of glutathione-S-transferases (GSTs) and manganese superoxide dismutase (MnSOD/SOD2) genes involved in the defence against oxidative damage has been investigated. Ninety cases of MPM and 395 controls were genotyped using the arrayed-primer extension technique. Logistic regression analysis was applied to assess the predictive role of single nucleotide polymorphisms (SNPs) potentially involved in MPM carcinogenesis after adjustment for potential confounders. An increased risk of MPM was found in subjects bearing a GSTM1 null allele (OR = 1.69, 95% CI = 1.04-2.74; p = 0.034), and in those with the Ala/Ala genotypes at codon 16 within MnSOD (OR = 3.07, 95% CI = 1.55-6.05; p = 0.001). A stronger effect of MnSOD was observed among patients without a clear exposure to asbestos fibres. No effect was found for GSTA2, GSTA4, GSTM3, GSTP1 and GSTT1 genes. These findings, if replicated, contribute substantial evidence to the hypothesis that oxidative stress and cellular antireactive oxygen species systems are involved in the pathogenesis and in the natural history of MPM.

Polyflex stents for malignant oesophageal and oesophagogastric stricture: a prospective, multicentric study.

OBJECTIVE: Dysphagia is the most distressing symptom in patients with cancer-related oesophageal obstruction. Endoscopic palliation aims to restore swallowing, avoid reintervention and to reduce hospitalization. This study reports an experience with a new self-expandable plastic stent (Polyflex) in patients with unresectable oesophageal and oesophagogastric junction cancer. METHODS: Sixty patients were prospectively collected. The cause of obstruction was oesophageal squamous cell carcinoma (44) and adenocarcinoma (eight), lung cancer (seven) and thyroid tumour (one). RESULTS: The stent was successfully placed in 59 patients. Early minor complications occurred in 19 patients (32%), and major complications in 13 (22%). Death occurred in three patients owing to pulmonary embolism (one) and massive haemorrhage (two). Recurrent dysphagia for early stent migration was observed in seven patients. Delayed stent migration occurred in five patients and tumour overgrowth in eight patients. The mean dysphagia score of 2.8 improved to a mean score of 1.0 after stenting (P<0.001). Overall median survival time was 4.6 months. CONCLUSIONS: Our study suggests that Polyflex stents are competitive with metal stents, with similar efficacy but lower cost. Technical improvements, however, are required to make these stents more user friendly. Large randomized clinical studies are needed to guide in the choice among the different available stents.

Mucosectomy for high-grade dysplasia in Barrett's esophagus.

Reports on the natural history of high-grade dysplasia (HGD) are sometimes contradictory, but suggest that 10-30% of patients with HGD in Barrett's esophagus (BE) will develop a demonstrable malignancy within five years of the initial diagnosis. Surgery has to be considered the best treatment for HGD or superficial carcinoma, but is contraindicated in patients with severe comorbidities. Non-surgical treatments such as intensive endoscopic surveillance, endoscopic ablative therapies, and endoscopic mucosal resection (EMR) have been proposed. EMR is a newly developed procedure promising to become a safe and reliable non-operative option for the endoscopic removal of HGD or early cancer within BE. It is important to assess the depth of invasion of the lesion and lymph node involvement before choosing EMR. This technique permits more effective staging of disease obtaining a large sample leading to a precise assessment of the depth of malignant invasion. Complications such as bleeding and perforation may occur, but can be treated endoscopically. Trials are needed to compare endoscopic therapy with surgical resection to establish clear criteria for EMR and ablative therapies.

Decline in serum carcinoembryonic antigen and cytokeratin 19 fragment during chemotherapy predicts objective response and survival in patients with advanced nonsmall cell lung cancer.

BACKGROUND: The authors assessed the predictive and prognostic role of decline in the serum levels of carcinoembryonic antigen (CEA) and cytokeratin 19 fragment (CYFRA 21-1) during chemotherapy in patients with advanced nonsmall cell lung cancer (NSCLC). METHODS: Changes in serum levels of CEA and CYFRA 21-1 during first-line, conventional chemotherapy were studied prospectively with an immunometric assay at baseline and every 2 courses in 117 patients with advanced NSCLC. Data were correlated with radiologic objective response (OR) and survival. RESULTS: One hundred seven patients were evaluable for radiologic and serologic response assessment after 2 chemotherapy courses. The radiologic OR rate was 44% overall. The CEA and CYFRA 21-1 responses (> or =20% reduction over baseline level; assessed after the second course of chemotherapy) were 38% and 61%, respectively. Statistically significant correlations were observed between CEA and CYFRA 21-1 responses and OR (P = .01 and P = .004, respectively). The median survival from response assessment (landmark analysis) was 9 months. In a univariate analysis, disease stage, performance status, baseline lactate dehydrogenase level (LDH), OR, CEA response, and CYFRA 21-1 response were correlated significantly with survival. In particular, the median survival was 13 months for patients who had a CEA response and 11 months for patients who had a CYFRA 21-1 response compared with 8 months and 6 months for patients who did not respond, respectively. In a multivariate analysis, performance status (P = .005), baseline LDH level (P = .02), CEA response (P = .03) and CYFRA 21-1 response (P = .01) were confirmed as independent prognostic factors for survival. CONCLUSIONS: CEA and CYFRA 21-1 responses appeared to be reliable surrogate markers of chemotherapy efficacy in patients with advanced NSCLC.

Endoscopic mucosal resection of large hyperplastic polyps in 3 patients with Barrett's esophagus.

AIM: To report the endoscopic treatment of large hyperplastic polyps of the esophagus and esophago-gastric junction (EGJ) associated with Barrett's esophagus (BE) with low-grade dysplasia (LGD), by endoscopic mucosal resection (EMR). METHODS: Cap fitted EMR (EMR-C) was performed in 3 patients with hyperplastic-inflammatory polyps (HIPs) and BE. RESULTS: The polyps were successfully removed in the 3 patients. In two patients, with short segment BE (SSBE) (<= 3 cm), the metaplastic tissue was completely excised. A 2 cm circumferential EMR was performed in one patient with a polyp involving the whole EGJ. A simultaneous EMR-C of a BE-associated polypoid dysplastic lesion measuring 1 cm multiply 10 cm, was also carried out. In the two patients, histologic assessment detected LGD in BE. No complications occurred. Complete neosquamous re-epithelialization occurred in the two patients with SSBE. An esophageal recurrence occurred in the remaining one and was successfully retreated by EMR. CONCLUSION: EMR-C appears to be a safe and effective method for treating benign esophageal mucosal lesions, allowing also the complete removal of SSBE.

Trends in incidence rates of oesophagus and gastric cancer in Italy by subsite and histology, 1986-1997.

OBJECTIVE: Population-based studies in Western countries suggest that the incidence of oesophageal adenocarcinoma (OA) and gastric cardia adenocarcinoma (GCA) is increasing, whereas the incidence of distal gastric carcinoma and oesophageal squamous cell carcinoma (OSCC) is declining. This is the first population-based study carried out in a southern European region to evaluate the time trends in incidence rates of oesophageal and gastric tumours according to subsite and histology over the period 1986-1997. METHODS: Cancer cases were drawn from seven registries of the Italian Network of Cancer Registries, which covers approximately 9% of the Italian population (annual average 5 027 944). Time trends in age and sex-standardized incidence rates were reported. Estimated annual percentage changes (EAPC) and related 95% confidence intervals (CI) were estimated by modelling age, sex, subsite and morphology-specific incidence rates through Poisson log-linear regression, and whenever necessary negative-binomial regression. Overall, 25 895 gastric and 2497 oesophageal carcinomas were examined. RESULTS: On the whole, an increasing trend was observed for OA plus GCA. The increase was statistically significant in younger women (<60 years: EAPC 3.7; 95% CI 0.2; 7.3) and in older men (>75 years: EAPC 4.0; 95% CI 1.2; 6.9). Similar trends were also observed in proximal gastric cancer (GCA plus fundus). A decline in the stomach subfundus incidence was observed in both sexes and in each age group. OSCC decreased significantly in men (EAPC-2.6; 95% CI-4.1;-0.9). CONCLUSIONS: It is plausible that the different tendencies in oesophageal and proximal gastric cancer in men and women are attributable to heterogeneous distributions of risk factors by sex or age.

Metabolic genotypes as modulators of asbestos-related pleural malignant mesothelioma risk: a comparison of Finnish and Italian populations.

The role of CYP1A1, GSTM1, GSTT1, EPHX1, and NAT2 genotypes in susceptibility to malignant mesothelioma (MM) was compared in two case-control studies, previously conducted in two countries where different types of asbestos fibers have been used [Hirvonen et al., 1995. Inherited GSTM1 and NAT2 defects as concurrent risk modifiers in asbestos-related human malignant mesothelioma. Cancer Res. 55, 2981-2983; Hirvonen et al., 1996. Glutathione S-Transferase and N-Acetyltransferase genotypes and asbestos-associated pulmonary disorders. J. Natl. Cancer Inst.88, 1853-1856; Neri et al., 2005. Pleural malignant mesothelioma, genetic susceptibility and asbestos exposure. Mutat. Res. 592, 36-44]. Fifty-seven asbestos-exposed MM patients and 255 controls were recruited in Italy, 48 cases and 121 controls in Finland. In order to make the two studies comparable, they have been updated and new genotyping analyses have been performed. The NAT2 fast acetylator and EPHX1 low-activity genotypes were positively associated with MM in the Italian study, while they were negatively associated with this malignancy in the Finnish one. A combined significant effect was also observed in the Italian study for the NAT2 fast acetylator and EPHX1 low-activity genotypes, while this combination was protective in the Finnish study. Combination of NAT2 fast acetylator and GSTM1 null genotype posed a significantly increased risk of MM in the Italian, but not in the Finnish study. The opposite results obtained in Finland and Italy may be ascribed to random chance, but a role may be hypothesized for the fact that different types of asbestos have been used in the two countries.

Endoscopic mucosal resection.

Endoscopic mucosal resection (EMR) is a promising therapeutic option for removal of superficial carcinomas or premalignant lesions throughout the gastrointestinal tract. This review discusses indications and the several techniques of EMR in early tumors of esophagus, stomach, duodenum, and colon. EMR is not yet widely utilized in the West. However, great benefits may be obtained from this non-invasive technique after an accurate evaluation of patients and a careful staging of lesions that may assess the depth of infiltration and exclude the presence of lymph node metastases. EMR permits a complete removal of the lesion with histologic assessment of the entire specimen and the change in the pathologic stage in a significant number of patients. To minimize the risk of serious complications (mostly bleeding and perforation), only experienced endoscopists should undertake EMR in an appropriate environment. Data from literature are encouraging on the use of EMR, but a long-term follow-up of a large number of patients is necessary to confirm the effectiveness of this therapy.

Functional analysis of c-Met/hepatocyte growth factor pathway in malignant pleural mesothelioma.

c-Met receptor tyrosine kinase (RTK) has not been extensively studied in malignant pleural mesothelioma (MPM). In this study, c-Met was overexpressed and activated in most of the mesothelioma cell lines tested. Expression in MPM tissues by immunohistochemistry was increased (82%) in MPM in general compared with normal. c-Met was internalized with its ligand hepatocyte growth factor (HGF) in H28 MPM cells, with robust expression of c-Met. Serum circulating HGF was twice as high in mesothelioma patients as in healthy controls. There was a differential growth response and activation of AKT and extracellular signal-regulated kinase 1/2 in response to HGF for the various cell lines. Dose-dependent inhibition (IC50 < 2.5 micromol/L) of cell growth in mesothelioma cell lines, but not in H2052, H2452, and nonmalignant MeT-5A (IC50 > 10 micromol/L), was observed with the small-molecule c-Met inhibitor SU11274. Furthermore, migration of H28 cells was blocked with both SU11274 and c-Met small interfering RNA. Abrogation of HGF-induced c-Met and downstream signaling was seen in mesothelioma cells. Of the 43 MPM tissues and 7 cell lines, we have identified mutations within the semaphorin domain (N375S, M431V, and N454I), the juxtamembrane domain (T1010I and G1085X), and an alternative spliced product with deletion of the exon 10 of c-Met in some of the samples. Interestingly, we observed that the cell lines H513 and H2596 harboring the T1010I mutation exhibited the most dramatic reduction of cell growth with SU11274 when compared with wild-type H28 and nonmalignant MeT-5A cells. Ultimately, c-Met would be an important target for therapy against MPM.

Pleural malignant mesothelioma, genetic susceptibility and asbestos exposure.

Pleural malignant mesothelioma (MM) is a rare but extremely aggressive cancer. The limited impact of standard therapeutic treatments on survival rates makes the identification of factors that increase the individual risk a leading priority. The high proportion of cases explained by exposure to asbestos has guided intervention policies to an effective ban of this compound from our environment. However, MM cannot be solely attributed to this agent, and the role of predisposing factors and their interaction with asbestos exposure is increasingly studied. The role of mEH, GSTM1, GSTT1, NAT2, and CYP1A1 genotypes in modulating susceptibility to MM was examined in a case-control study of 80 subjects with a confirmed diagnosis of MM and 255 controls. Subjects with low mEH activity showed a significantly increased risk of MM (OR, 2.51; 95% CI, 1.11-5.68). The association was stronger in the group with low asbestos exposure (OR, 7.83; 95% CI, 0.98-62.60). A significant increased risk of MM was also found in NAT2 fast acetylators (OR, 1.74; 95% CI, 1.02-2.96). The presence of synergisms between genotypes, i.e., mEH and NAT2 (LRT for heterogeneity p<0.023), mEH and GSTM1 (LRT p<0.061), and NAT2 and GSTM1 (LRT p<0.049), combined with the interaction observed with exposure to asbestos, suggests the presence of gene-environment and gene-gene interactions in the development of MM, although the size of the study group does not allow to draw clearcut conclusions. Since genetic polymorphisms can also modify the extent of genetic damage occurring in subjects exposed to carcinogens, we measured the frequency of micronuclei in peripheral blood lymphocytes of a subgroup of MM cases. The limited number of cases (28) did not allow to observe significant effects. In conclusion, these results strengthen the hypothesis that individual susceptibility to MM can be modulated by the interaction between polymorphic genes involved in the metabolism and the intensity of asbestos exposure.

Endoscopic treatment of high-grade dysplasia and early cancer in Barrett's oesophagus.

Barrett's oesophagus is the premalignant precursor of oesophageal adenocarcinoma. Non-dysplastic metaplasia can progress to low-grade dysplasia, high-grade dysplasia, and finally to invasive cancer. Although the frequency of adenocarcinoma in patients with Barrett's oesophagus is low, surveillance is justified because the outcome of adenocarcinoma is poor. Oesophagectomy remains the standard treatment for patients with high-grade dysplasia and superficial carcinoma. However, it has been associated with substantial morbidity and mortality and some patients are judged unfit for surgery. In this review, the present status of less invasive procedures is discussed. Endotherapy preserves the integrity of the oesophagus and allows a better quality of life to patients at low risk of developing lymph-node metastases. Opposition to endoscopic treatment is based mainly on the identification of undetected foci of cancer and high-grade dysplasia in oesophagectomy samples. The current ablative techniques used are photodynamic therapy, argon plasma coagulation, laser treatment, and endoscopic mucosal resection.