The role of polio-vaccine in pleural mesothelioma--an epidemiological observation.

From the Croatian Cancer Registry (period 1991-1997) 194 malignant pleural mesothelioma patients were collected. According to participation in polio vaccination mass campaign in 1961 that covered the entire Croatian population aged 3 months to 20 years, mesothelioma patients were divided in vaccinated (N=58), and non-vaccinated (N=136) subjects. Significantly higher percentage of those with a history of occupational exposure to asbestos was found in vaccinated (79%) compared to non-vaccinated group (63%). This is the opposite to what would be expected if potential SV40 contamination of polio vaccine used had a causative role in the development of the tumour. On the other hand, shorter latency period reflected by very high percentage of 45-year-old or younger mesothelioma patients in vaccinated group (15 out of 58), with all of them having a history of occupational asbestos exposure, raises a question for a possible enhancing effect of the vaccine used to asbestos exposure, if it was contaminated with SV40.

Incidence of malignant pleural mesothelioma in coastal and continental Croatia: epidemiological study.

AIM: To evaluate the actual incidence of malignant pleural mesothelioma in Croatia, geographical distribution of the disease, and relevance of occupation and some other characteristics of diseased subjects. METHOD: Data on the incidence of pleural mesothelioma over a seven-year period (1991-1997) were collected from the Croatian Cancer Registry. In each case, the tumor diagnosis was histologically verified. Registration of the patients was based on their place of residence. Also, in 2001, a short questionnaire was sent to patients' families to gather additional information on patients' occupation (exposure to asbestos), smoking habits, and length of residence in the registered place. In many cases some of the answers had to be clarified by telephone or through a personal contact. Data obtained from 20 counties (administrative units) of Croatia were grouped into two larger areas: coastal and continental. The data for the city of Zagreb were presented separately. RESULTS: During the 1991-1997 period, the Registry recorded a total of 248 malignant pleural mesotheliomas (197 in men and 51 in women). The poll gathered additional data for 194 patients (78.2%): 153 (77.7%) men and 41 (80.4%) women. Eight in a million people on average were diagnosed with malignant pleural mesothelioma per year. Age standardized incidence rates (per 100,000) by residence showed an uneven geographical distribution for men: 2.66 in coastal area, 0.69 in continental area, and 0.75 in the city of Zagreb. Goodness-of-fit test for observed rates vs expected for Croatia were chi-square=145, df=2, p<0.001; post-hoc tests: coastal vs continental area chi-square=12.3, df=1, p=0.001; and coastal area vs city of Zagreb chi-square=4.4, df=1, p=0.035. In women with mesothelioma, these rates were 0.38, 0.24, and 0.18, respectively, and the differences were not statistically significant. CONCLUSION: Assuming that the information obtained by the poll on the occupation of diseased subjects was a true characterization of all recorded cases of pleural mesothelioma, more than two-thirds of subjects with the studied tumor had an occupational exposure to asbestos. Uneven distribution of the tumor, with higher rate in men in the coastal area, may be related to shipbuilding and other industrial sources of asbestos exposure in that part of the country.