Germ Cell Tumors with Malignant Somatic Transformation: A Mayo Clinic Experience

Background: Germ cell tumors (GCTs) with malignant somatic transformation (MST) represent an uncommon variant of what is typically a curable malignancy. There is a paucity of data on time of somatic transformation, response to conventional therapy, and survival outcomes of different somatic subtypes. Methods: After obtaining institutional review board (IRB) approval, we searched our institutional database from 1982 to 2017 and identified patients with GCTs with MST. Patient characteristics, pathologic description, treatment, and clinical outcomes were extracted from the medical records. Results: We identified 24 cases of GCTs with MST; the MST was adenocarcinoma in 50% and sarcoma in 50%. Median age at diagnosis was 27. Alpha-fetoprotein and beta-human chorionic gonadotropin were undetectable in 44%, both were elevated in 54%. The majority were advanced stage (71% stage III), and International Germ Cell Cancer Collaborative Group (IGCCCG) risk was classified as 'good' in 60%. Median follow-up was 41 months (range 10-346 months). Median progression-free survival was 84 months (95% confidence interval (CI) 56-232), and median overall survival was 219 months (95% CI 165-not reported). Conclusion: Patients with GCTs with an MST appear to have poor responses to cisplatin-based chemotherapy, suggesting that somatic component-driven therapies should be considered. Furthermore, resection of residual disease when feasible is an essential component of management.