Drinking a lot of water and still urinating little after chemotherapy should alert you to the fact that it is chemotherapy-induced tumor lysis syndrome, which in turn leads to renal failure. Hepatic and renal impairment is a common adverse reaction to most chemotherapeutic drugs. Renal impairment after chemotherapy will lead to low urine output, and patients are advised to drink more water to accelerate renal excretion. If you drink a lot of water and still urinate less, you should be alert to tumor lysis syndrome. Tumors that are highly sensitive to chemotherapy, such as small cell lung cancer, leukemia, lymphoma, etc., will kill a large number of cancer cells and release a large number of cytokines or inflammatory molecules, which will be deposited on the surface of renal basement membranes and renal tubular cells, resulting in renal failure and urinary insufficiency. Urine volume and renal function indexes should be closely detected during chemotherapy. If patients experience oliguria after chemotherapy, they should communicate with their specialists and adjust the treatment plan in time.