International Journal of Radiation Oncology*Biology*Physics
Clinical investigation: sarcomaWhole abdominopelvic radiotherapy for desmoplastic small round-cell tumor
Introduction
Desmoplastic small round-cell tumor (DSRCT) is a rare, recently described, aggressive neoplasm with unique clinical, histologic, and biologic features 1, 2. It is primarily found in adolescent boys. Patients typically present with a bulky intraabdominal and/or pelvic, peritoneal-based mass (Fig. 1). More recently, extraserosal primary sites have also been reported 3, 4, 5, 6, 7. DSRCT belongs to the family of small, round, blue cell tumors of childhood, yet distinct characteristics distinguish it (8). The appearance of nests of tumor cells invested in a cellular desmoplastic stroma and polyphenotypic differentiation by immunohistochemistry is a classic finding for this entity (9). A novel reciprocal translocation, t(11:22)(p13:q12), has been identified in DSRCT that results in the fusion of the amino-terminus of the Ewing’s sarcoma gene (EWS) and the carboxy-terminus of the Wilms’ tumor gene (WT1) 10, 11, 12, 13, 14, 15. The EWS-WT1 chimeric transcript can be detected by cytogenetic analysis and polymerase chain reaction-based assays and is increasingly used to confirm the diagnosis 16, 17.
Clinically, these tumors are characterized by an extremely poor prognosis. Clinicopathologic studies and case reports have demonstrated rapid disease progression and a poor response to conventional chemotherapeutic regimens 8, 9, 18. Surgical debulking is limited by the diffuse nature of the peritoneal disease and direct visceral organ invasion 19, 20. The pattern of spread is similar to ovarian cancer, with dissemination throughout the serosal surfaces of the abdomen and pelvis. Because of this propensity for intraabdominal spread, whole abdominopelvic irradiation (WAPI) was introduced for consolidation after maximal surgical resection and to boost to areas of gross disease in the abdomen or pelvis.
The objective of this study was to retrospectively review our single institution experience with WAPI to evaluate its feasibility and role as part of a combined modality protocol for patients with DSRCT. This is the only known series to date reporting radiation techniques, toxicities, and outcomes of WAPI for this disease.
Section snippets
Methods and materials
Between 1992 and 2001, 21 patients were treated with WAPI for DSRCT at our institution. Four patients were included in a previous report 10, 21. Tissue diagnosis was determined by immunohistochemistry in all patients, and by polymerase chain reaction for the EWS-WT1 chimeric transcript in 15 patients. Pathologic specimens were centrally reviewed at our institution. All patients provided informed consent for treatment in accordance with institutional review board guidelines. The treatment plan
Patient characteristics
The patient age range was 8–34 years (median 16.5). The male/female ratio was 20:1. Of the 15 patients tested, polymerase chain reaction findings were positive for the EWS-WT1 chimeric transcript in 13 patients (87%). Fourteen patients were previously untreated and 7 had been referred to our institution for refractory or relapsed disease. All 21 patients were treated with at least 1 cycle of chemotherapy using the P6 regimen. Other chemotherapeutic agents, such as cisplatin, carboplatin,
Discussion
DSRCT remains a therapeutic challenge. Although it has gained recognition as a distinct entity among the small round-cell tumors of childhood on the basis of its unique clinical, histopathologic, immunophenotypic, and molecular genetic features, it is still a poorly understood neoplasm. The cell of origin in DSRCT is still unclear, although some investigators have proposed a “mesothelioblast” because of the serosal distribution and absence of a primary parenchymal site (23). The identification
Conclusion
The overall prognosis in DSRCT remains poor. Despite aggressive multimodality therapy, including intensive chemotherapy, surgical debulking, and EBRT, the treatment of patients with this rare and highly lethal disease is limited by its diffuse nature and chemoresistance. The results of this study demonstrate that WAPI is feasible in conjunction with intensive chemotherapy and surgery and, in exceptional cases, may contribute to a durable remission. Hematologic and GI toxicities are expected but
References (28)
- et al.
Desmoplastic small round cell tumor with primary ovarian involvementCase report and review
Gynecol Oncol
(2000) - et al.
Intra-abdominal desmoplastic small cell tumorA light microscopic, immunocytochemical, ultrastructural, and flow cytometric study
Hum Pathol
(1993) - et al.
A recurring translocation, t(11,22)(p13;q11.2), characterizes intra-abdominal desmoplastic small round-cell tumors
Cancer Genet Cytogenet
(1993) - et al.
Desmoplastic small round cell tumour of the pleuraA case report with further cytogenetic and ultrastructural evidence of “mesothelioblastemic” origin
Eur J Surg Oncol
(1999) - et al.
Case 2Desmoplastic small cell tumor with divergent differentiation
Pediatr Pathol
(1989) - et al.
Intraabdominal desmoplastic small-cell tumors with divergent differentiationObservations on three cases of childhood
Am J Surg Pathol
(1990) - et al.
Primary desmoplastic small cell tumor of soft tissues and bone of the hand
Am J Surg Pathol
(1999) - et al.
Disseminated intrathoracic desmoplastic small round-cell tumorA case report
J Pediatr Hematol Oncol
(1997) - et al.
Intracranial desmoplastic small-cell tumorReport of a case
Am J Surg Pathol
(1996) - et al.
Desmoplastic small round cell tumors of the paratesticular regionA report of six cases
Am J Surg Pathol
(1997)