Abstract 751P
Background
Fibrosarcoma is a rare malignant neoplasm representing 10% of musculoskeletal sarcomas and less than 5% of all primary bone tumors. It is classified as infantile fibrosarcoma (IFS) and adult-type fibrosarcoma. Second primary malignancies (SPMs) are a potential serious risk that can occur in fibrosarcoma survivors. Since there are no available studies analyzing this issue, we aimed to assess the risk of SPMs following primary fibrosarcoma diagnosis for better understanding of the nature of this rare neoplasm.
Methods
We selected patients diagnosed with fibrosarcoma from 2000 to 2021 using SEER*stat software. We used an MP-SIR session to calculate the standardized incidence ratio (SIR) as Observed/Expected (O/E) and the excess risk (ER) per 10,000. We subgrouped them histologically: IFS, fibromyxosarcoma, periosteal fibrosarcoma, facial fibrosarcoma, dermatofibrosarcoma, central odontogenic fibrosarcoma and ameloblastic fibrosarcoma.
Results
Out of 12783 fibrosarcoma patients, 1048 (8.2%) developed SPMs. The majority were Caucasians (71.1%) and 50.2% were females. A significant risk of SPMs was observed in all sites (O/E=1.46, P<0.05, ER=35.21). However, IFS had no risk to develop SPMs (Observed=1, O/E=1.85, P>0.05, ER= 4.26). Dermatofibrosarcoma had a high SPMs risk (O/E=1.52, P<0.05, 95% CI: 1.41-1.64) and fibromyxosarcoma had an O/E of 1.40 (P<0.05, 95% CI: 1.24-1.58). Fibromyxosarcoma had an alarming risk for SPMs if originated in the heart and soft tissue (O/E=32.38, P<0.05, 95% CI: 23.2-43.9). The risk of SPMs was notably higher in the young age (O/E=5.21, P<0.05). Respiratory system SPMs had an increased risk among fibrosarcoma survivors (O/E=1.84, P< 0.05, 95% CI: 1.03-3.04, ER=10.53). Fibrosarcoma had statistically insignificant risk to develop bone SPMs (Observed=1, O/E=1.00, P>0.05).
Conclusions
The results of this study reveal high risk of multisystem SPMs following primary fibrosarcoma especially for caucasians and females. However, IFS had insignificant risk of SPMs compared to adult-type fibrosarcomas. The most frequent sites for SPMs were the heart and soft tissue across all races, genders, ages, and histological types. Thus, more attention is needed for SPMs screening after the diagnosis of adult-type fibrosarcomas.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.