Desmoplastic small round cell tumor: A series of patients surgically treated at a single institution.

Abstract

e23555 Background: Desmoplastic small round cell tumor (DSRCT) is an ultra rare sarcoma predominantly involving the abdomino-pelvic peritoneum and mostly occurring in male children and young adults. It is marked by the EWSR1-WT1 fusion gene. Prognosis is poor with reported 5-year overall of < 20%. Methods: Data of patients with primary intra-abdominal DSRCT, who had surgery at our institution between 2000 and 2020, were analyzed. Information regarding disease presentation, cytoreductive surgery (CRS) with or without hypertermic intraperitoneal chemotherapy (HIPEC) and perioperative treatments were reported. Kaplan-Meier survival analysis was performed for both the whole cohort (A) and separately for peritoneal (B) vs peritoneal + lymphnode involvement (C) at disease presentation. Also, patients who underwent CRS alone vs CRS + HIPEC were compared. Results: 43 patients (pts) were identified, only 18 (42%) underwent surgical resection with curative intent in addition to perioperative chemotherapy (CT) ± radiotherapy (RT). 6 pts had also synchronous abdominal nodal metastases and one resectable liver metastases. Median tumor size was 19cm (12-20). 9 pts received pre and postoperative chemotherapy (CT), 7 pts preoperative CT, 2 pts postoperative CT. Postoperative abdominal RT was administered in 3 pts. Partial response (PR) to preoperative CT was observed in more than 50% of pts. Complete cytoreduction was achieved in 14 pts (78%). HIPEC was performed in 5 patients (28%). Overall, 8 pts died (44%), 1 patient after developing liver and lung metastases while 7 had peritoneal and intra-abdominal lymphnode recurrence. Of 10 patients alive, 7 had a recurrence. Of them, 5 are alive with disease (1 presenting extra-abdominal recurrence, 3 lymph node involvement and 1 liver metastases) at 75, 38, 33, 15 and 31 months, respectively, from diagnosis. 2 are alive without disease (after having a further surgery for local recurrence) at 35 and 36 months, respectively, from diagnosis. 3 patients are alive without disease at 12, 64, and 213 months from diagnosis. As a result, 5-year OS was 39.6%, 35.6% and 40% for group A, B and C, respectively. Median survival time was 39.2, 39.2 and 57.7 months for group A, B and C, respectively. 5-year OS was 35.2% and 50% for CRS and CRS + HIPEC group respectively. Conclusions: Despite an intense multimodal approach, DSRCT prognosis remains poor. CRS may improve oncologic outcomes. Our data confirmed significant tumor shrinkage after administration of preoperative CT which may be helpful to achieve macroscopically complete resections. The value of HIPEC and radiation therapy is more controversial and needs to be further investigated in a larger series. Interestingly, the presence of synchronous nodal metastases was not a negative survival prognosticator showing comparable outcome to peritoneal disease.