Session Item

Ewing sarcoma (EWS) is a heterogeneous and aggressive group of disease with a major incidence in adolescent and young adults. In patients eligible for upfront chemotherapy followed by local excision, pathological response is correlated with disease control and improved resection quality. Radiotherapy is frequently combined to surgery, in particular following poor response to chemotherapy and marginal resection, although it is unclear if preoperative administration may result in improved tumor regression and increased local control. 

The main aim of the study is to evaluate the determinants of local control in surgically treated EWS and the impact of preoperative radiotherapy in terms of pathologic response and resecability.

Data of consecutive EWS patients treated with induction chemotherapy and surgical excision between July 2002 and January 2020 were retrospectively reviewed. Local Control (LC) was defined as the time interval from diagnosis to local relapse. Tumor response was graded according to the Picci score. Statistical analysis was performed to assess correlation between clinical and pathological features and outcome.

Thirty-nine patients were included in our study. Skeletal and extra-skeletal disease were found in 33 (84%) and 6 (16%) patients, respectively. Primary tumor was located on the trunk in 46% of cases (n=18) and limbs in 54% of cases (n=21). Metastatic disease was present at diagnosis in 38% (n=15) of patients.

All patients received preoperative chemotherapy followed by surgical excision, resulting in a 90% R0 resection rate. Radiotherapy was administered in 21 (54%) patients to a median dose of 54 (range 42-54) Gy in 36 (range 28-36) fractions, consisting of preoperative and postoperative irradiation in 10 (26%) and 11 patients (28%), respectively. 

Pathological response was scored grade 1 (n=30, 77%), 2 (n=2, 5%) and 3 (n=7, 18%). After a median follow-up of 22 months (range 8-72 months), 6 local recurrence occurred.

Local control (LC) was 92% at 1 year and 85% at 2 years. At univariate analysis, only primary tumor location in the trunk was correlated with impaired LC (median not reached, p=0.018). Use of preoperative radiotherapy was neither significantly correlated with grade 3 complete tumor response (24% versus 20% p=0.79) nor positive margin status (8% versus 20%, p=0.24).

From our analysis it emerged that the only prognostic factor affecting local control is the primary location of the disease, and in particular trunk sites have a worse outcome compared to limbs sites. In our cohort, preoperative radiotherapy did not impact neither on local control nor on the incidence of complete response and clear margin resection. Further studies should explore the possible interest of preoperative radiotherapy in high risk patients with primary trunk EWS.