Differential Diagnoses And Mesothelioma Cases

The mesothelioma differential diagnosis present the usual limitation: a lack of precision related to the retrospective mode of collecting in a survey.

13 suspected cases of pleural cancer (8 men, 3 of whom were Melanesians; 5 women, 4 of whom were Melanesians) were eliminated from the study by the National Committee of Mesothelioma and/or by the Certification Committee because there was incomplete histological information or insufficient proof.  The diagnosis of mesothelioma was possible, but there was insufficient clinico-pathological evidence, and the experts were unable to make an alternative diagnosis.  Therefore, the number of observed cases may have been understated, and the real over-incidence may have been slightly higher than that observed.

We did not find a risk of pleural cancer in the nickel workers in New Caledonia.  The comparison of New Caledonia with more developed regions (e.g., New York State, which presented an excess of pleural mesothelioma for men and women compared with other states), showed that other industries that are usually at risk for mesothelioma (e.g., naval construction and repair, insulation, manufacture of asbestos-based    products) were not implicated.

Before 1994, health officials had no uniform way of tracking cancers in the state. Since then, all diagnosed cancer cases have been reported to the Health Department as part of the Minnesota Cancer Surveillance System. The system allows health officials to spot cancer trends. But it doesn't offer information such as where the victims worked.

An environmental risk is plausible.  The geographical distribution of the pulmonary cancer cases that were collected during the first 4y of the study (1996-2000) indicates a relationship between these cancers and zones of residence. Environment and lifestyle could account for this relationship.  However, the risk of pleural cancers in New Caledonia is between 2 and 5 times higher than in the regions included by the reference registers.  This is much lower than the risks observed in other parts of the world (e.g., more than 1 000 times in a region of Turkey).

Health officials say the rate for women living in the region is well below the state average. That tells epidemiologists that asbestos exposure likely is not occurring in the general population. If it were, the rates among men and women would be comparable.

A qualitative examination of case residence histories did not afford the establishment of a relationship with a particular area of the country, even with the region on the east coast north of Touho, which is the richest region in natural fibers.  Nor was there a relationship with proximity of nickel mining sites, the dust from which could contain natural fibers in very limited quantities.  However, the small excess of risk could be attributed to low exposure to a yet-unidentified agent. Some authors suggest that when occupationally unexposed cases are younger (in this study two women were 31 and 35 y of age), the cause might be environmental.

The preliminary result of mesothelioma differential diagnosis must be confirmed, and it would be of interest to examine the presence and type of fibers in the atmosphere.

Mesothelioma Patient