Fibrosarcoma is a malignant tumor originating from mesenchymal tissues and consists of fibroblasts with various types of collagen production. It represents 10% of musculoskeletal sarcomas and less than 5% of all primary bone tumors. It affects middle-aged patients with the most common location in the femur and 70% long tubular bones. Studies reported that fibrosarcoma patients tend to develop a subsequent primary malignancy, the analysis showed a higher risk of SPMs even a decade following the initial diagnosis of fibrosarcoma.

SPMs affect the long-term survival of patients with soft tissue tumors, and since there are no available studies analyzing the risk of second primary malignancies in different types of fibrosarcomas, especially the infantile and adult-type. Therefore, the purpose of this study was to assess the risk of second primary malignancies following primary fibrosarcoma diagnosis for a better understanding of the nature of this rare neoplasm. The investigators used the Surveillance, Epidemiology and End Results (SEER) database to extract the data and calculate the standardized incidence ratio as Observed/Expected and the Excess risk for second primary malignancies with 95% Confidence Interval. Significance was achieved at 0.05.

Inclusion Criteria:

• Patients diagnosed with fibrosarcoma from 2000 to 2021.
• Sequence 0 or 1.
• Histological types:

Infantile fibrosarcoma, Fibromyxosarcoma, Periosteal fibrosarcoma, Facial fibrosarcoma, Dermatofibrosarcoma, Central odontogenic fibrosarcoma, Ameloblastic fibrosarcoma

Exclusion Criteria:

• Patients with unknown histology type

The study included 12,783 patients diagnosed with fibrosarcoma between 2000 and 2021.