Incidence and survival of mesothelioma in Osaka, Japan.

BACKGROUND

Mortality statistics show rapid increase in the number of deaths from mesothelioma. However, population-based study of the incidence and the survival has never been conducted. Time-trends and regional differences in the incidence of mesothelioma in Osaka were examined together with their 5-year survival.

METHODS

Individual data for mesothelioma were retrieved from Osaka Cancer Registry during the period 1966-2001. Annual incidence rates were calculated for every 3 years from 1975 to 2001, and age-standardized rates were calculated with the Japanese model population of 1985. Standardized incidence ratios were also calculated by age-specific number of population of each municipality and the corresponding age-specific incidence rates of mesothelioma in Osaka Prefecture during the period 1981-2001. The survival analysis was performed with the Kaplan-Meier method, based on the newly reported cases diagnosed during the period 1975-1997.

RESULTS

Incidence rates of mesothelioma have increased rapidly both among males and females in Osaka during the past few decades. Geographical differences in the standardized incidence ratios were found to be remarkable in Osaka Prefecture. The result shows that the survival of malignant mesothelioma was very poor (5-year survival and median survival time: 5.1% and 6 months for males, 10.2% and 5 months for females).

CONCLUSIONS

Incidence of mesothelioma has increased remarkably in Osaka, Japan, during past few decades. Geographical variations in the incidence were also suggested. Five-year survival of the patients was very poor.