OBJECTIVETo explore the effect of neo-adjuvant chemotherapy and computer-assisted surgery on children and adolescents with primary pelvic Ewing's sarcoma, and assess the therapeutic effect on the pelvic skeletal growth and development.

METHODSThis is a retrospective analysis of 10 children with primary pelvic Ewing's sarcoma treated between Jan 2001 and Oct 2010 at the Department of Oncologic Orthopaedics at Xijing Hospital. There were 3 girls and 7 boys in the age of 7 to 16 years (average 12.7 years). All patients were pathologically diagnosed as Ewing's sarcoma. There were two cases in the sacroiliac joint, one in the ilium, one in the pubic bone, and 6 cases in peri-acetabular area including 5 below the triradiate cartilage and one above the triradiate cartilage, without cartilage invasion. All patients underwent neo-adjuvant chemotherapy, resection and reconstruction surgery and postoperative chemotherapy. CDP, ADM and IFO regimen chemotherapy were given as the main treatment. Five cases were treated by traditional resection and reconstruction, and after 2008, five cases were treated by computer-assisted surgery. During the reconstruction, the hip rotation center was put at a depressed location. All of the 10 cases underwent postoperative radiotherapy in a dose of 45-55 Gy.

RESULTSAll patients were followed-up for 12-72 months (mean: 37.8 months). One child had tumor recurrence and lung metastasis and 9 patients had no evidence of disease (NED). After neo-adjuvant chemotherapy, the oncologic statuses (RECIST) were: 1 CR, 8 PR and 1 SD. The functional recoveries after surgery (Enneking's) were: 4 cases excellent, 4 good, 1 fair and 1 poor. Five cases who underwent computer-assisted surgery achieved a good reconstruction without local recurrence. There were no effects on skeletal growth in 8 cases. An unbalanced hip rotational center occurred in one case, and a compemsatory scoliosis was found in another case. There were no serious complications in all patients.

CONCLUSIONSThe comprehensive treatment including neo-adjuvant chemotherapy, resection-reconstruction surgery and postoperative chemoradiotherapy may give a good control to primary pelvic Ewing's sarcomas in children and adolescents. The computer-assisted surgery used for accurate tumor resection and pelvic reconstruction is a good alternative when treating young patients with malignant pelvic tumors. The triradiate cartilage in children's acetabulum could be a natural barrier resistant to the invasion of Ewing's sarcomas.