Supplementary Material for: A case of tumor lysis syndrome during palliative radiotherapy for breast cancer metastases

Tumor lysis syndrome (TLS) is the rapid disintegration of a malignant tumor treated with anticancer drugs or radiation, causing electrolyte abnormalities such as elevated uric acid levels, elevated potassium and phosphorus levels, and decreased calcium levels. These abnormalities can lead to hypotension, renal dysfunction, consciousness disorders, and even death in some cases. The current patient was a 65-year-old woman who had breast cancer with local invasion, lung metastasis, and bone metastasis from the time of the initial disease onset. Despite the administration of various chemotherapy and hormone therapy regimens, the tumor increased gradually, and at 2 years and 5 months after the initial onset, pain and bleeding from metastatic infiltration of the cervical lymph nodes were noted. Therefore, radiotherapy was indicated for palliation of pain and bleeding caused by metastatic invasion of the cervical lymph nodes. Irradiation (30 Gy/10 fr) was performed with a 3-field technique using 4MVX and 10MVX. Approximately 11 h after the initial irradiation, symptoms such as respiratory distress, tachycardia, and hypotension were observed. Blood tests revealed hyperuricemia and hyperkalemia, leading to a diagnosis of TLS. Dialysis and electrolyte correction were immediately initiated resulting in normalization of electrolytes and stabilization of the blood pressure. It is crucial to understand that TLS is relatively rare but can occur after radiation therapy or in solid tumors, and warrants a prompt response if suspected based on symptoms or blood findings.

肿瘤溶解综合征（Tumor lysis syndrome, TLS）是接受抗肿瘤药物或放射治疗的恶性肿瘤快速崩解所引发的病症，可导致血尿酸升高、血钾及血磷升高、血钙降低等电解质紊乱。此类电解质异常可引发低血压、肾功能不全、意识障碍，部分病例甚至可导致死亡。
本次病例为一名65岁女性患者，初诊时即患有伴局部浸润、肺转移及骨转移的乳腺癌。尽管接受了多种化疗及激素治疗方案，肿瘤仍逐渐进展；在初诊后2年5个月时，患者出现颈部淋巴结转移灶浸润引发的疼痛与出血。因此，为缓解颈部淋巴结转移浸润所致的疼痛与出血，给予放射治疗。治疗采用三野技术，联合4MVX与10MVX射线，处方剂量为30 Gy/10次分割。
首次放疗后约11小时，患者出现呼吸窘迫、心动过速及低血压等症状。血液检查提示高尿酸血症与高钾血症，据此确诊为肿瘤溶解综合征。随即启动透析与电解质纠正治疗，患者电解质恢复正常，血压得以稳定。
需明确的是，肿瘤溶解综合征相对罕见，但可发生于放射治疗后或实体瘤患者中，若基于症状或血液检查结果怀疑该病，需及时采取应对措施。