Abstract
AIMS: To evaluate the clinical impact of excision repair cross-complementation group 1 (ERCC1) expression in high-grade osteosarcoma (OS). METHODS AND RESULTS: Immunohistochemistry was performed on biopsies from 99 OS patients enrolled in the ISG/OS-Oss training set or ISG/SSG1 validation set neoadjuvant chemotherapy protocols, based on the use of cisplatin, adriamycin, methotrexate, and ifosfamide. In the training set, ERCC1 positivity was found in eight of 31 (26%) patients, and was significantly associated with worse event-free survival (EFS) (P = 0.042) and overall survival (OVS) (P = 0.001). In the validation set, ERCC1 positivity was found in 22 of 68 (32%) patients, and its significant associations with poorer EFS (P = 0.028) and OVS (P = 0.022) were confirmed. Multivariate analyses performed on the whole patient series indicated that ERCC1 positivity was the only marker that was significantly associated with a higher risk of worse prognosis, in terms of both EFS and OVS (P = 0.013). Co-evaluation of ERCC1 and ABCB1 expression showed that patients who were positive for both markers had a significantly worse prognosis. CONCLUSIONS: The ERCC1 level at diagnosis is predictive for the outcome of patients with non-metastatic, high-grade OS treated with neoadjuvant chemotherapy, and co-evaluation with ABCB1 can identify high-risk groups of OS patients who are refractory to standard regimens.