Occupational asbestos exposure and digestive cancers - a cohort study.

BACKGROUND: Although the role of asbestos in the genesis of mesothelioma and primary bronchopulmonary cancers has been established, results from studies focusing on the relationship between occupational exposure to asbestos and digestive cancer remain contradictory. AIM: To determine whether occupational asbestos exposure increases the incidence of digestive cancers. METHODS: Our study was a retrospective morbidity study based on 2024 subjects occupationally exposed to asbestos. The incidence of digestive cancer was calculated from 1st January 1978 to 31st December 2004 and compared with levels among the local general population using Standardized Incidence Ratios. Asbestos exposure was assessed using the company's job exposure matrix. RESULTS: Eighty-five cases of digestive cancer were observed within our cohort, for an expected number of 66.90 (SIR = 1.27 [1.01; 1.57]). A significantly elevated incidence, particularly notable among women, was observed for peritoneal mesothelioma, independently of exposure levels. A significantly elevated incidence was also noted among men for cancer of small intestine and oesophagus, for cumulative exposure indexes for asbestos above 80 fibres/mL x years. A significantly elevated incidence of cancer of the small intestine was also observed among men having been exposed to asbestos for periods in excess of 25 years and for mean exposure levels in excess of 4 fibres/mL. CONCLUSIONS: This study suggests the existence of a relationship between exposure to asbestos and cancer of the small intestine and of the oesophagus in men.

Incidence of digestive cancers and occupational exposure to asbestos.

While the role of exposure to asbestos in the development of several cancers such as mesotheliomas and bronchopulmonary cancers is now well established, the possible relationship between digestive cancers, other than peritoneal mesotheliomas, and occupational exposure to asbestos is still controversial. The great majority of the studies are based on mortality data. The aim of the study was to analyse the relationship between digestive cancer incidence and occupational exposure to asbestos in a population of subjects for whom precise occupational exposure data and precise incidence data were available. The population consisted of salaried and retired workers from a company using asbestos to manufacture fireproof textiles and friction materials. There were 1454 men (79.9%) and 366 women (20.1%). A cumulative exposure index and a mean exposure concentration in fibres/ml for each subject were calculated with the aid of an in-house job-exposure matrix. The number of cases of digestive cancer observed was compared with the expected and Standardized Incidence Ratio (SIR) was estimated. Precise occupational exposure data allowed us to study the dose-response relationship between asbestos exposure and risk of digestive cancer using Cox model. Fifty-six digestive cancers occurred in the study population over the 18-year follow-up period for 48.4 expected (SIR = 1.16 [0.87-1.50]). Comparing with incidence in the county, SIR was not significant for any of the digestive localization, but for peritoneum. However, even after taking into account the potential confounders via the Cox model, there was a significant dose-response relationship between the occurrence of digestive cancers and the mean exposure concentration, even after exclusion of peritoneum cancers. Our study provides initial evidence suggesting a relationship between occupational exposure to asbestos and the risk of digestive cancer: first, it is a study of incidence although the risk evidenced is not significant; secondly, a dose-effect relationship is demonstrated in the whole population. However, these preliminary results require confirmation by more powerful studies focusing on larger series.

[Malignant mesothelioma in Basse-Normandie, a French population study. Descriptive analysis, prognostic factors and survival]. / Mésothéliomes malins en Basse-Normandie: analyse descriptive, facteurs pronostiques et survie. Une étude de population.

BACKGROUND: Malignant mesothelioma is a pleural and/or peritoneal tumor closely related to asbestos exposure, and its incidence should continue to increase during the first two decades of the 21(rst)century. The main prognostic factors described for this tumor are older age, sex, tumor stage and histological type. The aim of this study was to assess the incidence of pleural and peritoneal malignant mesothelioma in the County of Basse-Normandie (France), as well as their epidemiological characteristics, and the prognostic factors related to survival duration. METHODS: Cases were identified through repeated inquiries among all chest physicians and pathologists of the County of Basse-Normandie. A special care was taken in the validation of the diagnosis of each case. Incidence of mesothelioma was determined according to sex and age (5 years categories). Qualitative and quantitative variables were compared with the use of chi-square or Student's t tests respectively. Survival rate was calculated by Kaplan-Meier method, and prognostic factors were studied by means of Cox model. RESULTS: Study population consisted in all 80 malignant mesothelioma cases diagnosed in Basse-Normandie between the 1(rst) of September 1995 and the 31(rst) of August 1999. Annual incidence rates of pleural mesothelioma were 1.1/100 000 in men and 0.23/100 000 in women; annual incidence rates for peritoneal mesothelioma were 0.21/100 000 in men and 0.13/100 000 in women. Asbestos exposure was present in 63 cases (78.8%). The study of geographic distribution of mesothelioma cases revealed the influence of the main asbestos industrial settings, as well as the numerous scattered cases related to other occupational exposure. Mean survival duration was 9 months for pleural mesothelioma and 5 months for peritoneal mesothelioma. After adjustment on age, death risk was higher in asbestos-exposed than in non asbestos-exposed cases. CONCLUSION: This study confirms that malignant mesothelioma is closely related to asbestos exposure, but not only in main asbestos industrial settings. It suggests that asbestos exposure may take place among prognostic factors of this tumor.

[Rectal resection for cancer in Lower-Normandy. Loco-regional recurrences and survival. Results of a regional survey (1988-1993)]. / La résection rectale pour cancer en Basse-Normandie. Récidives loco-régionales et survie. Résultats d'une enquête régionale (1988-1993).

OBJECTIVES AND METHODS: A retrospective regional study was set up to identify the determinants of loco-regional recurrences and those of survival after rectal resection for cancer. The studied population was constituted of 505 patients with resection for carcinoma of the rectum in Lower-Normandy from 1988 to 1993. RESULTS: The actuarial rate of loco-regional recurrence was 17.3 +/- 4% at 3 years. The only significant predictive factor of survival free of loco-regional recurrence was the Dukes' stage. Actuarial survival rate was 52.0 +/- 4% at 5 years, the corresponding relative survival rate being 64.6 +/- 6%. The only two independent prognostic factors were the sphincter-saving procedure and adjuvant radiotherapy. COMMENTARIES: The loco-regional recurrence rate after resection for rectal cancer is still high. Sphincter-saving procedure and adjuvant radiotherapy increase over the time. Since the study was retrospective, no definitive conclusions could be drawn. Nevertheless, they incite us to set up larger prospective regional studies including quality control of surgical procedures, radiotherapy protocols and histopathological reports.

Recent time trends in cancer of the oesophagus and gastric cardia in the region of Calvados in France, 1978-1995: a population based study.

The incidence of oesophageal cancer differs from country to country, and even between areas of the same country. Many studies in recent years have shown an upward trend of a particular histologic type: adenocarcinoma of the oesophagus. It is difficult to precisely locate adenocarcinomas situated at the junction between the oesophagus and the gastric cardia. Clear criteria to define and classify such tumours are essential in order to analyse their evolution. The present study describes the changing incidence of cancers of the oesophagus and gastric cardia according to histologic type from 1978 to 1995 in Calvados, the highest-risk French region with two different topographic classifications of adenocarcinomas: one based on Misumi's criteria and the other based on local extension of cancer. In total, 1835 cancers of the oesophagus and gastric cardia were diagnosed in this period. Incidence rates for oesophageal and gastric cardia cancers standardized on the world population were 24.4/10(5) and 2.4/10(5) in men and 1.4/10(5) and 0.4/10(5) in women, respectively. The time trend in the incidence of squamous cell cancers was downward in men -0.74 (P < 10(-6)) and stable in women +0.04 (P = 0.65). Regarding adenocarcinomas, with the classification based on Misumi's categories, there was a slight but significant upward trend for oesophageal adenocarcinoma in men [mean annual variation of +0.09 (P < 10(-5))] while the tendency was downward and significant for gastric cardia adenocarcinoma [mean annual variation of -0.09 (P < 10(-4))]. When adenocarcinomas of the oesophagus and those of the gastric cardia with oesophageal involvement are taken together (second classification), there was an upward trend which was not significant in men and was significant in women. There was no such upward trend in adenocarcinomas limited to the gastric cardia and/or involving the stomach. Because of the difficulties in determining accurate localization routinely in population-based studies, it seems sensible to preclude classification biases in recommending the grouping together of gastric cardia adenocarcinomas with oesophageal adenocarcinomas, at least with those among the latter occurring in the lower third of the oesophagus.

Social environment and prognosis of colorectal cancer patients: a French population-based study.

Colorectal cancer is a major public health problem in industrialised countries. Several studies have shown that social environment influences survival in cancer patients in many countries, but the causes remain unknown. In France, very little work has been done in this area. Our aim was to assess whether social environment influences survival of colorectal cancer patients in a well-defined French population and, if so, to what extent this could be explained by differences in stage at diagnosis or in treatment. The study population consisted of 1,642 colorectal cancer patients diagnosed between 1978 and 1987 in the French department of Calvados. Socio-demographic characteristics were assessed in terms of socio-professional category, place of residence (urban vs. rural) and distance from the place of residence to a specialised health-care centre. The relation between social environment, clinical factors and survival was studied using 2 multivariate methods (Cox model and relative survival method). Patients with poorer prognosis were found to be farmers of both sexes and individuals without occupation among males. Differences in survival were not explained entirely even when variations in stage at diagnosis and in treatment were taken into account.

[Mass screening of colorectal cancer by general practitioners in France: what is the real target population?]. / Le dépistage de masse du cancer colo-rectal par les médecins généralistes en France: quelle est la vraie population cible?

OBJECTIVES: People at high risk of colorectal cancer, due to familial or personal history, or to specific symptoms, are considered not to be concerned by mass screening by Haemoccult test. The aim of this study was to investigate people aged 50 to 74 with high risk of colorectal cancer among general practitioners' practices in the department of Calvados (France). METHODS: A random sample of 200 general practitioners were asked to systematically fill out a questionnaire on Haemoccult II proposal for 50-74 year-old patients for a whole week. RESULTS: Participation rate of general practitioners was 58.5%. According to our findings, 13% of 50-74 years patients are considered not be concerned by mass screening, due to familial or personal history, or to specific symptoms. CONCLUSIONS: Colorectal cancer screening protocol have to be fit to level of risk of colorectal cancer. Involvement of general practitioners in colorectal cancer mass screening allows identification of high risk people who can then be managed with a more suitable screening protocol.

[Mass screening for colorectal cancer in France. Experience in 165,000 people in the department of Calvados]. / Le dépistage de masse du cancer colorectal en France. Expérience auprès de 165,000 personnes dans le Calvados.

OBJECTIVES: Screening for colorectal cancer is a major public health problem in France as in most developed countries. Several controlled trials are on-going in Europe. The aim of the study was to determine requirements for success of mass-screening for colorectal cancer in France. METHODS: A mass-screening program has been conducted between April 1991 and June 1994 in the department of Calvados for 164,364 people aged 45-74 years. The screening test was first proposed by general practitioners and occupational doctors during appointments. Secondly, a postal invitation to obtain the test, free of charge, by doctor or chemist, was sent. RESULTS: Global participation rate was 43.4%; 40.2% of tests were distributed during the first phase, 47.1% during the second phase and 12.7% were distributed by a private health institute. Participation was higher for females (47.1%) than males (39.2%) and for urban districts (46.5%) than rural districts (24.4%). In case of positive test, colonoscopy has been more frequently achieved in urban districts and when test has been distributed by a physician. Positivity rate was 2.8%. Positive predictive value was 8.0% for a cancer and 13.5% for an adenoma larger than 1 cm. Because both positivity rate and positive predictive value were higher for males than females and increased with age, rate of cancer or large adenoma screened was almost three times higher for males than females and markedly increased with age. CONCLUSIONS: In France, different recruitment methods have to be used to reach a satisfactory participation to a mass-screening campaign. Such a program requires involvement of general practitioners and close coordination between practitioners and health care insurance agencies.