Growth patterns of osteosarcoma predict patient survival

In this retrospective study, we assessed tumor growth patterns as visualized on MR images, and examined whether tumor growth patterns correlate with clinicopathologic variables. In addition, we also evaluated the relationship between patient outcome and tumor growth pattern in the whole study cohort and in subsets of AJCC IIA and IIB patients. We retrospectively reviewed 347 patients with Enneking stage IIB and AJCC stage II osteosarcoma that was treated with surgery and neoadjuvant chemotherapy at our institute. Patients were divided into three groups based on tumor growth pattern, namely, concentric, eccentric, and longitudinal groups. Fisher's exact test was performed to analyze correlations between tumor growth patterns and clinicopathological variables. Five-year metastasis-free survival and overall survival were evaluated using univariate and multivariate analyses. In terms of tumor growth patterns, 225 patients (64.8%) had a concentric, 71 (20.5%) an eccentric and 51 (14.7%) a longitudinal tumor. Eccentric tumors were usually small and responded well to chemotherapy, whereas concentric tumors were large and responded poorly. The prognostic significances of tumor growth patterns were confirmed by univariate and multivariate analyses. Among AJCC stage IIA patients, no survival difference was found according to growth pattern, whereas in AJCC stage IIB patients, longitudinal tumors were associated with significantly better survival than concentric tumors. Tumor growth pattern was found to be an independent prognostic factor in stage II osteosarcoma. Moreover, longitudinally growing tumors were associated with better survival in AJCC stage IIB patients. Our results suggest that tumor growth pattern could be used as an indicator of risk-adapted therapy when combined with other prognostic factors.