First case report of tumor lysis syndrome after third line systemic therapy with gemcitabine and pazopanib in a patient with lower extremity soft tissue sarcoma

Background: Tumor lysis syndrome (TLS) is recognized as an oncologic disorder with a variable incidence. TLS can cause the rapid destruction of tumor cells in response to oncologic therapy and is characterized by multiple electrolyte disturbances as well as its secondary complications, including death. This disease is common among patients with hematologic neoplasms, but very rare among those with solid tumors, as is the case with sarcomas. Such patients have a poor prognosis and increased risk of mortality. In the patient's particular case, this occurred after initiating third-line systemic therapy with gemcitabine associated with pazopanib, an event not previously described in the literature,Case Description: We report the case of a patient with a history of high-grade sarcoma of the left lower limb T4N1M0 stage IIIB undergoing surgical management and exhibiting tumor progression with the need for third-line systemic therapy with pazopanib and gemcitabine. The patient presented with pain at the amputation site, inflammatory changes, and a tumor mass of large components on admission. They later developed electrolyte imbalance and acute renal injury compatible with TLS after systemic therapy was initiated. Pharmacological therapy, including rasburicase, was initiated based on the clinical and laboratory findings. Due to the progression of renal involvement, it was necessary to initiate haemodialysis, and during her hospital stay, the patient presented febrile syndrome associated with pancytopenia. The patient showed a favourable clinical response to the proposed antibiotic therapy and recovery of renal function, for which reason therapy was restarted with pazopanib and gemcitabine, the latter with a 20% reduction for the following cycles. Outpatient follow-up continued, completing eight cycles of treatment with good tolerance and partial clinical response; the patient died of respiratory complications eight months after discharge. Conclusions: There is limited evidence for TLS in patients with high-grade sarcoma in the literature