Trends of centralization of childhood cancer treatment between 1975 and 2002 in Osaka, Japan.

Objective: To analyze the tendency to centralize childhood cancer treatment among cancer treatment hospitals in Osaka, Japan over a 28-year period.
Methods: The subjects were patients under the age of 15, newly diagnosed with cancer in Osaka between 1975 and 2002 (n = 4738). They were categorized into three groups by the time diagnosed (1975-84, 1985-93 and 1994-2002). The International Classification of Childhood Cancer was used as the disease classification. The degree of centralization was examined using a Pareto analysis, the Gini coefficient and the annual average number of cases per hospital.
Results: During this period, the number of children with cancer in Osaka has decreased by nearly half, from 2.1 to 1.2 million and the number of hospitals treating childhood cancer decreased from 37 to 20. However, the Pareto curve and Gini coefficient were almost constant (0.747, 0.737, 0.756 in Gini coefficient for the three diagnosed periods). The annual average numbers of cases per hospital were much low and marginally increased from 5.6 during 1975-84 to 6.1 during 1994-2002 in the hospitals that treated 90% of all cancers.
Conclusions: The degree of centralization appeared to be almost constant from 1975 to 2002 regardless of the decrease in hospitals treating cancer patients.