Roopmati, A 56-year-old female with lymph-node-positive breast cancer was treated with systemic chemotherapy. Four weeks later, she developed frequent urination, suprapubic pain, dysuria, and hematuria. Which of the following could have prevented this patient's condition?

The patient described in the question has hemorrhagic cystitis caused by drugs like cyclophosphamide and ifosfamide. Hemorrhagic cystitis during therapy with cyclophosphamide or ifosfamide is caused by the urinary excretion of the toxic metabolite acrolein. This can be prevented by aggressive hydration, bladder irrigation, and administration of mesna, compound that binds acrolein in the urine.