e18726 Background: Mediastinal germ cell tumor (MGCT) is a rare entity and comprises 10-15% of all mediastinal tumors. We describe the real-world treatment patterns and outcomes of MGCT treated at two tertiary care centres in India. Methods: Patients diagnosed with GCT (any site) at two large tertiary care centres from January 2010 to December 2020 in India were identified using the ICD-09 code (C-62) from prospectively kept databases. From these databases, a manual search was performed to identify MGCT patients. A chart review was done to retrieve demographic, tumor-related (serum tumor marker levels as per International germ cell cancer consensus (IGCCC)) and treatment details. Relapse free survival (RFS) and overall survival (OS) were estimated and compared for seminomatous and non-seminomatous MGCT. Results: A total of 54 patients were identified and all were males with a median age of 25 years (interquartile range, 18-45). Common presenting symptoms included cough (81.4%) shortness of breath (64.8%), chest pain (25.9%), superior vena cava obstruction (20.3%), pleural effusion (18.5%) and pericardial effusion (5.6%). Approximately one-thirds (n = 17) were seminomatous, while two-thirds were non-seminomatous (n = 37). Serum tumors markers levels were S0 (7.4%),S1 (42.6%),S2 (29.6%) and S3 (20.4%). Treatment was primarily by multiagent chemotherapy [ Bleomycin/Etoposide/cisplatin(BEP) 63.0%, EP (Etoposide/Cisplatin) 18.5%, VIP (etoposide/ifosfamide/cisplatin) 13.0%). Median number of cycles administered was 3 (Range 1-6). Three patients did not receive chemotherapy (all seminoma) and were treated with upfront surgery. In total, 11 patients (20.4%) underwent surgery, and eight (14.8%) received radiation. Three patients were not evaluable for response, 33.3% achieved complete response (CR),44.4% achieved partial response (PR), 9.3% had SD (stable disease) and 7.4% progressed on first line chemotherapy. Median follow up was 14.4 months (95% confidence interval [CI] 9.03 -26.16). Three year relapse free survival was 64.0% in overall population, and 100% in seminoma vs 41.5% in non-seminoma (P < 0.001). Three year OS was 80.2% in all patients and 94.1% for seminoma versus 70.0% in non-seminoma (P = 0.178). Conclusions: In this largest real-world analysis of MGCT, we found excellent long-term survival rates for patients with seminomatous MGCT, while further optimization of treatment is needed for those with non-seminomatous MGCT.
AB018. Advances in mediastinal tumors diagnosis: J. Rosai, a master of Pathology, and the value of morphology and related disciplines
