Skip to main content
CTOS 2023 Main banner
Final Program


Schedule at a Glance
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

Sarcoma of the Year: Small Round Blue Cell Tumor

(P 437) ULTRA-RARE UNDIFFERENTIATED SMALL ROUND CELL SARCOMA: HOW SHOULD WE TREAT THEM? AN ANALYSIS FORM THE GRACEFUL PROJECT

Location: The Liffey, Level 1
Objective: Undifferentiated small round cell sarcomas (URCSs) represent a diagnostic challenge, and their optimal treatment is unknown. We aimed to report on the treatment and outcome of patients (pts) affected by URCS within the an international study (GRACefUl Project; NCT05357768).

Methods: URCS pts treated from 1983 to 2019 at 31 worldwide sarcoma reference centres were retrospectively identified. Based on molecular assessment, cases were classified as follows: (1) CIC-rearranged round cell sarcomas, (2) BCOR::CCNB3-rearranged round cell sarcomas, (3) unclassified URCSs (uURCS), (4) other genomic alterations. Primary end-point was Progression-Free Survival (PFS) defined as the time of date of biopsy until first progression or death, whichever occurred first (not applicable for group 4). Secondary end-point was overall survival (OS), defined as the time from of date of biopsy until to death or last available follow-up.

Results: In total, 243 pts were retrospectively identified: 150/243 (61%) CIC-rearranged sarcoma (median age 32 years, range 7-86), 47/243 (19%) BCOR::CCNB3-rearranged (median age 17 years, range 5-91), 40/243(16%) uURCSs (median age 38 years, range 4-70), and 6/243 (2%) other genomic alterations: EWSR1-NFATC2 (n = 4), CIC-LEUTX (n = 1), FUS-NFATC2 (n = 1), respectively.
Clinical presentations and treatments are shown in Table 1. Surgery was performed in 187/231 (80.9%) of the patients, combined with radiotherapy in 72/231 (31.2%); chemotherapy was used in 199/232 (85.6%), with no difference among groups; Ewing regimen was the most frequently used in the different histotypes (Table 1).
Stage at diagnosis of 234 pts included in the survival analysis was localized/resectable in 132 (56.4%), advanced in102 (43.6%).
At a 39-month median follow-up (range 6-373), the 3-year progression-free survival (PFS) was 58.9% (95% CI 50-76) in BCOR::CCNB3 patients, 40.8% (95% CI 35-52) in CIC-rearranged sarcomas, and 61.8% (95% CI 52-80.0) in uURCs (p = 0.009). With the limitation of a small sample size, no significant different PFS for BCOR::CCNB3 pts treated with an Ewing regimen vs. those receiving an Osteosarcoma regimen was shown; similarly, no difference among CIC::rearranged sarcoma pts treated with a Ewing regimen vs. doxorubicin and ifosfamide combination was proven. Nonetheless, Ewing regimen compared with doxorubicin and ifosfamide seemed associated with better outcome in uURCS (p=0.046) (Table 2).
3-year OS (95%CI) was 94.9% (95% CI 88-100) in BCOR::CCNB3 patients, 41.4% (95% CI 34-51), in CIC-rearranged, and 71.7% (55.6-87.8) in uURCS (p=0.0005).

Conclusion: This analysis confirmed that URCS encompasses several distinct ultra-rare sarcomas which are treated with different approaches across institutions. Prospective studies are needed to better define the optimal treatment strategy in each URCS subtype, and in particular to understand whether there are subtypes in which an intensive Ewing regimen can improve the outcome.