Abstract
1. The incidence of osteogenic sarcoma, chondrosarcoma and Ewing's sarcoma in relation to age, sex and site is analysed in a study of 832 malignant primary bone tumours diagnosed in Sweden in 1958-68. The results are compared with those in other series.
2. The adolescent incidence peak for osteogenic sarcoma is caused by tumours localised to the long bones of the lower limb. The peak incidence occurs at a mean age of twelve years for girls and sixteen years for boys and is associated with the maximum growth velocity for the adolescent growth spurt.
3. Ewing's sarcoma, showing no sex difference with regard to its incidence peak, seems not to be associated with bone growth.
4. In the adult, the incidence of osteogenic sarcoma parallels that of chondrosarcoma, thus showing a successive increase with increasing age. In Sweden, where Paget's disease is uncommon, the incidence of osteogenic sarcoma over the age of thirty is only one-third of that during adolescence.
5. In osteogenic sarcoma and chondrosarcoma but not in Ewing's sarcoma, the characteristic predominance of males over females is valid only for localisations to the long bones of the lower limb, the pelvis and the spinal column and not for other sites. Internal factors such as age, sex, bone growth and maturation and also weight-bearing seems to be of importance in modifying the response of the tissue to a causative external factor, like a common virus.
