Prognostic impact of pulmonary nodules diagnosed at initial presentation in patients with osteosarcoma

Background: Resection of all lung metastases in patients with osteosarcoma improves survival. The increased computed tomography (CT) scan quality allows detecting smaller nodules. We aimed to evaluate the prognostic impact of those nodules that do not meet the classical criteria for lung metastases.

Methods: A central radiology review (CRR) on lung CT scans performed during the treatment of patients included in OS2006 trial and treated with a high-dose methotrexate-based chemotherapy from 2007 to 2013 was realized in three centers.

Results: At trial enrollment, among 77 patients, six (8%) had nodules meeting the trial's criteria for metastatic disease, 46 (60%) were classified as having localized disease, and 25 (32%) as having doubtful nodules. After CRR, 218 nodules were found at diagnosis (all in patients classified as "metastatic or doubtful" and 13 patients classified as "localized") (median two nodules per patient [1-52]). The 5-year event-free survival/overall survival (EFS/OS) of patients with at least one nodule versus no nodule were similar (67.7%/79.2% vs. 81.8%/91%). After histological analysis, two of 46 (4.3%) "localized" and eight of 25 (32.0%) "doubtful" patients were re-classified as "metastatic," whereas there was no change in patients initially "metastatic." The 5-year OS of confirmed histological metastatic versus nonmetastatic patients were different (56% vs. 92%, p < .01).

Conclusion: Central review of lung CT scan increased the detection of nodules in osteosarcoma. Patients with small lung nodules classified as doubtful had a quite similar outcome as those with a localized disease. However, patients with confirmed metastatic nodules have a poorer prognosis, even if considered as "localized" at diagnosis.