554 Background: The main objective of this study was to determine the clinical features, treatment, clinical outcome and prognosis of Down's syndrome (DS) patients with germ cell tumor (GCT). Methods: Literature search based on PubMed search was performed using the following keywords: “Germ cell tumor (GCT)” and “Down's syndrome”. A total of 85 cases of GCT in DS patients published in literature between January 1985 and October 2017 were identified. Results: Our final cohort of GCT in DS include 44 cases of testicular germ cell tumor (TGCT); 22 intracranial GCT, 2 primary mediastinal GCT, 3 gastrointestinal GCT, 9 retroperitoneal GCT, and 5 cases of ovarian GCT. The median age of forty-four testicular GCT was 30 years (range 2 years – 50 years). In most cases, cancer was diagnosed following the discovering of swelling by care provider or found incidentally (either painless or painful) in the region of the testes, although abdominal pain was a symptom in a few cases. 29 (66%) patients were diagnosed with seminoma and 15 (34%) with non-seminoma. In the seminoma group, 18 (62%) patients were diagnosed with stage I , 9 (31%) with stage II and 2 (7%) with stage III. In the non-seminoma group, 4 (27%) patients were diagnosed with stage I, 5 (33%) with stage II and 6 (40%) with stage III. Nearly all patients (94%) underwent orchiectomy. 52% patients received chemotherapy, with BEP being the most common administered regimen. 7 patients had retroperitoneal lymph node dissection ( RPLND). In the seminoma group, there were 5 deaths, 3 related to disease progression, 2 related to comorbidities, 1 died during chemotherapy. In the non-seminoma group, there were 2 deaths, 1 related to disease progression, 1 died during chemotherapy. The overall survival at 5 years for stage I was 100%, 76% for stage II and 68% for stage III. Conclusions: In this largest cohort of GCT in DS, we found TGCTs are often diagnosed at stage II or III. In addition, delayed diagnosis, comorbidities likely contributed to the inferior outcome in stage II/III TGCTs in patients with DS. Emphasis on education, better communication, early screening and detection, are needed to improve the outcome in this population.
MP49-06 NATIONWIDE PATTERNS OF CARE FOR STAGE II NON-SEMINOMATOUS GERM CELL TUMOR: RPLND AND CHEMOTHERAPY UTILIZATION