Tumor Lysis Syndrome in a Patient with Metastatic Endometrial Cancer Treated with Lattice Stereotactic Body Radiotherapy

Abstract Introduction Lattice stereotactic body radiotherapy (SBRT) is a form of spatially fractionated radiotherapy that potentially allows for the safe delivery of ablative radiation doses to bulky tumors. Tumor lysis syndrome (TLS) is most often seen in patients with hematologic malignancies treated with chemotherapy. Radiation-induced TLS in patients with solid tumor malignancies is uncommon. We describe a case of a patient who presented with radiation-induced TLS following Lattice SBRT. Case Report A 85-year-old-female with chronic kidney disease (CKD) stage III and metastatic clear cell endometrial cancer was treated with Lattice SBRT to 20Gy in 5 fractions with 66.7Gy delivered simultaneously to spherical vertices spaced within the GTV on a phase 2 clinical trial. Treatment was delivered every other day. 13 days following completion of radiotherapy the patient presented with syncope and possible seizure and was found to have bradycardia, shock, acute renal failure, and biochemical abnormalities consistent with TLS. She was admitted to the intensive care unit and discharged to hospice shortly after. Discussion The traditional definition of TLS requires presentation within 7 days of initiation of chemotherapy. In this case, the constellation of biochemical derangements associated with a 28% tumor shrinkage over two weeks status post radiotherapy is suggestive of TLS. Risk factors for TLS for this patient included a relatively radiosensitive tumor histology and baseline CKD. As a result of this sentinel event, the phase II clinical trial has been amended to monitor for TLS following treatment with Lattice SBRT.