Rare bone sarcomas: A retrospective analysis of 145 adult patients from the French Sarcoma Group

The benefit of chemotherapy (CT) in rare bone sarcomas is not documented in prospective studies. Our retrospective study from the French sarcoma network for bone tumors ResOs was performed in adult patients (pts) from 1976 to 2014, with histologically verified diagnosis of leiomyosarcomas (LMS), undifferentiated pleomorphic sarcoma (UPS) or radiation‐associated sarcomas of bone. The median follow‐up was 4.7 years (95% CI: 3.7‐6.5). Clinical features, treatment modalities and outcomes were recorded and analyzed from 145 pts (median age 53 years [range 20‐87]). Site of disease was extremities (66%) or axial skeleton (34%), 111 (77%) presented with localized and potentially resectable disease. The most common histological subtypes were UPS (58%) and LMS (33%); 58% were high‐grade tumors. Surgery was performed in 127 pts. In the 111 localized pts, 28 pts (25%) underwent upfront surgery or exclusive radiotherapy (RT; >50 Gy) without CT, whereas 83 pts (75%) received either neoadjuvant (n = 26) or adjuvant CT (n = 13) or both (n = 44). Neoadjuvant and adjuvant CT was mostly doxorubicin‐based (95%/86%) and cisplatin‐based (67%/63%). R0 resection was achieved in 59 pts, and a good histological response in 15 patients (25%). Adjuvant RT was performed in 24 (22%) pts. For the whole cohort (n = 145), the 5‐year overall survival (OS) rate was 53% [42; 62]. In univariate analysis, age ≤ 60 was associated with a longer disease‐free survival (DFS) (P = .0436). Neoadjuvant and adjuvant CT tended to be associated with better DFS (P = .056) with no significant impact on OS in this retrospective series. What's new? Rarer types of primary bone sarcoma (non‐osteosarcoma, non‐chondrosarcoma, and non‐Ewing sarcoma) present a major diagnostic challenge, and are often excluded from clinical trials. In this study, the authors found that patients who had localized disease and were treated with both neo‐adjuvant and adjuvant chemotherapy tended to have better disease‐free survival (DFS). However, there was no significant impact on overall survival (OS). The role of adjuvant chemotherapy and radiation therapy remains unclear, which highlights the need for prospective randomised trials in these uncommon bone malignancies.