Abstract
Growing teratoma syndrome (GTS) is rare. It is fatal if the teratoma is unresectable. A standard systemic therapy is not established. The efficacy of interferon-alpha (IFN-α) for GTS was described but the treatment periods were relatively short. A 23-year-old Japanese male with bulky retroperitoneal lymph node and multiple lung metastases that progressed to GTS was administered 6 × 10(6) units of natural IFN-α 2 × /week. Since the IFN-α treatment suppressed both lesions' growth, it was continued for >10 years. The patient is well with controlled metastases (135 months since the IFN-α's initiation). This is apparently the longest follow-up of INF-α treatment for GTS.