The effectiveness of adjuvant therapy in adult patients with spindle cell/sclerosing rhabdomyosarcoma: A single-center retrospective study.

Abstract

e23550 Background: In recent years, the WHO classification of soft tissue tumours has classified spindle cell/sclerosing rhabdomyosarcoma (RMS) as a novel subtype of RMS. However, the prognosis and standard treatment modalities for operable spindle cell/sclerosing RMS patients remain unclear. This study aims to investigate the effectiveness and influencing factors of postoperative adjuvant therapy in adult patients with spindle cell/sclerosing RMS. Materials and Methods: This single-center retrospective study enrolled adult patients with spindle cell/sclerosing RMS who underwent surgery and subsequent adjuvant therapy at West China Hospital, Sichuan University, from August 2014 to March 2023. The included patients initially underwent surgical excision, followed by one of the adjuvant treatments: radiotherapy, chemotherapy, or a combination of radiotherapy and chemotherapy. Disease-Free Survival (DFS) and Overall Survival (OS) were calculated for the included patients in this study. Univariate analysis and multivariate COX regression were conducted to determine prognostic factors. Results: This study included a total of 17 patients diagnosed with spindle cell/sclerosing RMS. Among them, 10 (58.8%) patients received postoperative adjuvant chemoradiotherapy, while 7 (41.2%) patients underwent postoperative chemotherapy alone. 12 (70.6%) patients received chemotherapy following the VAC regimen, and 5 (29.4%) patients received non-VAC chemotherapy. The prognosis analysis indicates that the median DFS was not reached, with a 1-year DFS rate of approximately 87.8% and a 2-year DFS rate of approximately 52.4%. The median OS was not reached, with a 1-year OS rate of 100% and a 2-year OS rate of approximately 92.9%. Univariate analysis shows that compared to undergoing non-R0 resection, undergoing R0 surgical resection significantly improves patient DFS (P = 0.02). Compared to no postoperative radiotherapy, receiving postoperative prophylactic radiotherapy significantly improved both DFS (P = 0.01) and OS (P = 0.02). In contrast, using VAC as adjuvant chemotherapy did not significantly increase DFS and OS compared to non-VAC regimens (P = 0.83 and 0.57, respectively). Multivariate Cox regression analysis demonstrated that the receipt of postoperative prophylactic radiotherapy independently predicted DFS (P = 0.03). Conclusions: In adult patients with spindle cell/sclerosing RMS, R0 resection, when compared with non-R0 resection, delays disease recurrence but does not enhance overall survival. Long-term outcomes may be improved in patients who receive postoperative adjuvant radiotherapy. However, choosing a VAC regimen as adjuvant chemotherapy may not contribute to an improved long-term prognosis when compared with a non-VAC regimen. Keywords: adjuvant therapy, spindle cell, sclerosing, rhabdomyosarcoma, effectiveness