Bladder cancer in patients with multiple sclerosis treated with cyclophosphamide

Purpose: We define the risk of bladder cancer in multiple sclerosis related to the use of indwelling catheters and cyclophosphamide administered as an immunomodulating agent. Materials and Methods: We retrospectively reviewed the records of 2,351 patients with multiple sclerosis referred to the National Center for Multiple Sclerosis. Results: Of the 2,351 patients 2 women and 5 men (0.29%) had bladder cancer. Of the 850 chronically catheterized patients the incidence was 0.7%. One patient with cancer performed intermittent catheterization for a rate of 0.23% in this group. In a subgroup of 70 patients treated with cyclophosphamide 5 chronically catheterized patients (5.7%) had bladder cancer. Hematuria was the most common presenting symptom. These data were compared with those in the literature on bladder cancer in spinal cord injury. Conclusions: These data suggest a possible synergistic role of cyclophosphamide and chronic catheterization in the induction of secondary bladder cancer. Regular cystoscopy is warranted in these patients to allow early detection of bladder tumors. Nitric oxide metabolism may be an important factor in the carcinogenesis of this type of bladder cancer.