The metastatic patterns of osteosarcoma

The paper presents a detailed comparison of the anatomical distribution and frequency of clinically evident metastases in 152 cases of osteosarcoma, and autopsy findings in 43 cases. The behaviour of long bone tumours is contrasted with those arising elsewhere, which tend to metastasize less widely because of early death from effects of the primary tumour. In both clinical and autopsy series long bone tumours produced lung metastases (LM) in over 90% of patients dying with metastases, but the terminal frequency of extra-pulmonary metastases (EPM) rises from a clinical level of 33% to 83% at autopsy. There was little difference between tumours of the major long bones in the frequency of either LM or EPM, but EPM from the humerus tended to be fewer and sited above the diaphragm and from the femur below it. EPM most often involved other bones, notably vertebrae and pelvis. Not more than 10% of tumours invaded regional lymph nodes but terminally a quarter of the long bone tumours had metastasized to heart and abdomen. The infrequency of metastases in muscle was confirmed. The median time for LM was 5-6 months after starting treatment, for EPM 9-10. months. First metastases after 24 months were infrequent, especially in children. With delay in the appearance of metastases, whether LM or EPM, post-metastatic survival lengthened. Neither age, sex nor mode of treatment of the primary notably affected metastatic frequency, although recurrences were much more numerous when radiotherapy, even with high dosage, was the definitive treatment. Local recurrence usually appeared within 6-8 months and was shown to lead to increased frequency of osseous metastases. It is suggested that terminal dissemination may often be tertiary but not always from a pulmonary secondary.