PURPOSE Although substantial improvements in survival of childhood cancer have been achieved, information on long-term survival outside European countries and the United States is scarce. The aim of this study was to clarify the long-term trends and disparities in survival of childhood cancer in Japan. MATERIALS AND METHODS Using data from the Osaka Cancer Registry, trends in survival among patients age younger than 15 years diagnosed with cancer during 1976-2015 and followed up to 2020 were analyzed. Childhood cancers were defined and classified according to the International Classification of Childhood Cancer, Third Edition. The primary outcome measure was the probability of 5-year overall survival (OS) after diagnosis. RESULTS For all cancer groups combined, the 5-year OS increased substantially across the diagnosis periods (51.4% 95% CI, 49.3% to 53.5% in 1976-1985; 83.7% 95% CI, 81.8% to 85.4% in 2006-2015). The improvement in survival was most pronounced during the first 2 decades. Age-standardized 5-year OS was higher than 90% for lymphomas, retinoblastoma, renal tumors, and germ cell tumors in 2006-2015. There were wide varieties in the difference in 5-year OS by cancer type between 1976-1985 and 2006-2015, with the largest increase in leukemias and modest improvements in malignant bone tumors and soft tissue sarcomas. CONCLUSION OS for all cancers combined increased substantially during 1976-2015. The wide and persistent differences in survival outcomes suggest the need for novel strategies to improve outcomes for cancer types with the least changes in survival.
Tatara et al. (Sun,) studied this question.