BACKGROUND: @entity421 ( @entity421 ) manifestations distant from the site of the @entity5 rarely arise as only sign of disease recurrence. METHODS: This report reviews 38 @entity1 with high-grade central @entity421 of the limbs or axial skeleton and initial complete surgical remission (CR) who developed first recurrences as solitary osseous lesions distant from the @entity5 . The @entity421 Study Group (COSS) database was used to evaluate @entity1 -, @entity5 -, and treatment-related variables and outcomes. RESULTS: Thirty-eight @entity1 (27 males and 11 females; 36 limb and 2 axial primaries) developed solitary osseous recurrences a median of 2.1 years (range: 0.5-14.3) from primary diagnosis. Relapses involved axial (24), extremity (10), or craniofacial bones (4). Treatment for recurrence included surgery (28), radiotherapy (10), and chemotherapy (27). After a median follow-up of 1.9 years (range: 0.1-21.2) from first recurrence for all 38 @entity1 and 5.5 years (0.3-21.2) for 16 survivors (10 in continuous second CR), 2- and 5-year overall and event-free survival (EFS) probabilities were 55% and 34% and 34% and 27%, respectively. A long interval to recurrence (>1.5 years) predicted for better overall (P < 0.001) and EFS (P = 0.005). For 21 @entity1 achieving a second CR, 2- and 5-year overall and EFS probabilities were 81% and 61% and 52% and 49%, respectively, while only 1/17 others survived beyond 5 years (P < 0.001). Survivors (14/16) had also received second-line chemotherapy. CONCLUSION: First solitary skeletal recurrences of @entity421 should be treated with curative intent. Some presumed bone metastases may represent second primary OSs.

XXXX recurrence. Findings from the @entity421 Study Group.

@entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'primary tumor'] @entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity421 :: ('MESH:D012516', 'Disease') :: ['Cooperative Osteosarcoma', 'Solitary skeletal osteosarcoma', 'OS']
@entity421 :: (MESH:D012516,Disease) :: ['Solitary skeletal osteosarcoma']
