Epidemiology of osteosarcomas
The approximate annual incidence of osteosarcoma is 2-3 per million in the general population; it is <1 per million in children under the age of 5 years, 2 per million at the age of 5-9 years, 7 per million at the age of 10-14 years and peaks at 8-11 per million at the age of 15-19 years1.
There is a second smaller peak in older patients, which is due to osteosarcomas arising in abnormal bones, such as those affected by Pagetís disease or previously treated with radiotherapy.
Males are affected more frequently in most series (male: female ratio; 1.4:1). Osteosarcoma rates for girls up to about age 13 years are roughly 30% higher than those for boys. In the 15 to 24 year old age group, the male rate exceeds the female rate by some 140%.
It occurs in any bone of the body. Among young patients, the most common site is the metaphysis of a long bone. Approximately half of all osteosarcomas originate in the region around the knee.
The most frequent primary site is the distal femur, followed by the proximal tibia, followed by the proximal humerus (picture 1). Other primary sites in descending order of frequency are pelvis, jaw, fibula and ribs.
Osteosarcoma of the head and neck is more likely to be low-grade than osteosarcoma of the appendicular skeleton and is more likely to arise in older patients.
Picture 1: Out of 1649 osteosarcoma patients surveyed, number of patients at specific sites (Arndt et al., 1999 NEJM 342-352)