Osteosarcoma: Prognosis at Initial Diagnosis

Kaste et al and Bieling et al. have shown that measurements of osteosarcoma at diagnosis can be correlated with prognosis. The anteroposterior dimension of the tumor (tumor depth) and absolute tumor volume (see below for calculation) have been shown to be predictive of overall survival and event-free survival in patients with osteosarcoma.

Tumor depth is defined as the horizontal extent of osteosarcoma on a lateral radiograph. The risk of death has been shown to increase approximately 1.5 times for each centimeter increase in tumor depth. A 5-year event-free survival rate of about 80% was seen in patients with tumor depth ≤ 5 cm, while those with tumor depth of > 5 cm had an event-free survival rate of about 55%.

Absolute tumor volume is calculated as an ellipsoid: 0.52 x tumor length x tumor width x tumor height, all measured on radiographs. The 5-year overall survival rate for patients with tumor volume ≤ 150 cm³ has been shown to be about 85%, while that of patients with tumor volume > 150 cm³ has been shown to be about 60%. Looked at in another way, patients with absolute tumor volumes > 150 cm³ have been shown to be 3.6 times more likely to die compared to those with smaller tumor volumes.

References

• Bieling P, Rehan N, Winkler P, Helmke K, Maas R, Fuchs N, Bielack S, Heise U, Jurgens H, Treuner J, Romanowski R, Exner U, Kotz R, Winkler K. Tumor size and prognosis in aggressively treated osteosarcoma. J Clin Oncol. 1996 Mar;14(3):848-58.
• Kaste SC, Liu T, Billups CA, Daw NC, Pratt CB, Meyer WH. Tumor size as a predictor of outcome in pediatric non-metastatic osteosarcoma of the extremity. Pediatr Blood Cancer. 2004 Dec;43(7):723-8.