Epidemiology of malignant neoplasms in soft tissue during childhood

Employing the data of the Hokkaido Children's Cancer Registry, incidences of malignant neoplasms in soft tissue during childhood were estimated. During 25 years (1975--1999), a total of 110 such cases (0-14 years of age) were registered. The average incidence was 0.40 per 100,000 population aged 0-14 years. The incidence of rhabdomyosarcoma (RMS) was 0.24, accounting for 60% of all malignant neoplasms in soft tissue. 30% of the malignant neoplasms in soft tissue were found in the head/face/neck. The share of RMS in the upper limbs was 76%, while that in the chest was 25%. Mortality due to malignant neoplasms in soft tissue was estimated using the data of vital statistics of all Japan. The average mortality of all malignant neoplasms in soft tissue was about 0.15 per 100,000 population aged 0-14 years, which was almost constant throughout the 25 years. Both the mortality at 5-9 years of age and that at age 10-14 years increased, while that at 0-4 years had a tendency to decrease. The prolongation of the survival period in the 0-4-year age group due to the progress in therapy may have brought about a shift of the age at death to older age groups, leading to a decrease in the mortality at 0-4 years of age.