Background: Tumor lysis syndrome (TLS) is an oncologic emergency that can occur spontaneously or triggered by cancer treatment. This life-threatening condition is most commonly seen in hematologic cancers but is sometimes described in solid tumors such as germ cell tumors (GCTs). The objective of this study is to investigate the clinical characteristics and outcomes of TLS in GCTs.Methods: Retrospective review and pooled analysis.Result: Seventeen cases of TLS related to GCTs were identified. These included nonseminomatous GCT (7), seminoma (5), choriocarcinoma (2), ovarian (2), and intracranial germinoma (1). Nine cases (53%) of TLS were treatment-related and eight cases (47%) occurred spontaneously. The median age of patients was 34 years (range: 13-58), excluding one newborn baby. The median time from treatment to TLS was 2.1 days. Seven patients (41%) had liver metastases, but all patients had bulky disease. All of the patients received supportive measures; 4 (24%) patients received rasburicase and 11 patients (64%) underwent hemodialysis. The mortality rate was 44.4% among the nine cases of treatment-related TLS, and 37.5% in the eight patients with spontaneous TLS (STLS). Conclusion:TLS can occur in GCTs that have a high tumor burden. Almost 50% of TLS in GCTs happened spontaneously. Considering the life-threatening nature of TLS in GCTs, health care professionals should be alert and monitor for TLS in order to prevent or treat this potentially fatal complication.

533 Background: Genitourinary (GU) cancers account about 20% of all human cancer in the United States. Tumor lysis syndrome (TLS) is an oncologic emergency with few treatment options. While TLS has been extensively documented in patients with hematological malignancies, it is rarely described in patients with GU cancers. The objective of this study was to investigate the clinical characteristics and outcomes of TLS, a rare but life-threatening complication in GU cancers. Methods: Systematic review of the literature and pooled analysis of published cases of TLS in GU cancers. Results: A total of 180 patients with TLS in solid tumor were included in our study. The median age was 57 years (8-94). Male: female ratio was 1.7. The most common sites were gastrointestinal (29%); followed by genitourinary (22%); lung (16%); melanoma (11%), breast cancer (8.3%). Liver metastasis was documented in 70% of study subjects. TLS occurred as a consequence of cancer therapy in 68% of subjects; and spontaneously in 32% of subjects. Older age and liver metastasis predict high mortality. The clinical features, treatment and outcomes of TLS in 40 cases of GU cancers including testicular germ cell tumor (TGCT) (n=14), renal cell carcinoma (n=10), prostate cancer (n=15), penile cancer (n=1) and urothelial carcinoma (n=3) were compared. The mortality rate of TLS were 50% in TGCT, 70% in renal cell carcinoma, 64% in prostate cancer 67% in urothelial carcinoma. Conclusions: TLS in GU cancers is associated with very high mortality. TLS should be considered on the differential diagnosis, when evaluating renal failure and electrolyte derangement in patients with metastatic GU cancers with liver metastases. The clinical features and outcomes of TLS in genitourinary cancers. [Table: see text]