Unintentional Dual Benefit: Improvement in Secondary Polycythemia in a Patient Receiving Chemotherapy for Metastatic Clear Cell Renal Cell Carcinoma

Complete blood counts are frequently collected from cancer patients, but laboratory findings may be misleading. Secondary polycythemia can occur in renal cell carcinoma (RCC) due to erythropoietin (EPO) stimulation. Therefore, complete blood counts should be closely monitored to prevent complications such as thrombosis. We discuss the case of a 47-year-old man with metastatic RCC who presented with secondary polycythemia that improved with chemotherapy. His secondary erythrocytosis was anticipated, but his haemoglobin levels were lower than expected after therapy. This article discusses the treatment and diagnosis of secondary polycythemia in patients with RCC. LEARNING POINTS: Haemoglobin and haematocrit levels should be closely monitored in renal cell carcinoma (RCC) patients as they may develop secondary polycythemia as a result of their malignancy. Secondary polycythemia can be managed with chemotherapy and immunotherapy in RCC, with anti-cancer agents preventing the need for phlebotomy. Chemotherapy may benefit RCC patients by decreasing tumour burden, preventing progression, and by lowering haemoglobin levels, thus improving secondary polycythemia.