Successful Prevention of Tumour Lysis Syndrome in HER2-positive Breast Cancer: Case Report and Literature Review

Background/Aim: Tumour lysis syndrome (TLS) is a life-threatening oncological emergency. TLS is rare and associated with a higher mortality rate in solid tumours than in haematological malignancies. Our case report and literature review aimed to identify the distinctive features and hazards of TLS in breast cancer. Case Report: A 41-year-old woman complained of vomiting and epigastric pain and was diagnosed with HER2-positive, hormone-receptor-positive breast cancer with multiple liver and bone metastases and lymphangitis carcinomatosis. She had several risk factors for TLS: high tumour volume, high sensitivity to antineoplastic treatment, multiple liver metastases, high lactate dehydrogenase levels, and hyperuricaemia. To prevent TLS, she was treated with hydration and febuxostat. One day after the first course of trastuzumab and pertuzumab, she was diagnosed with disseminated intravascular coagulation (DIC). After 3 further days of observation, she was relieved of DIC and administered a reduced dose of paclitaxel without life-threatening complications. The patient achieved a partial response after four cycles of anti-HER2 therapy and chemotherapy. Conclusion: TLS in solid tumours is a lethal situation and can be complicated by DIC. Early recognition of patients who are at risk of TLS and initiation of therapy is essential to avoid fatal situations.