Background Cyclophosphamide is an alkylating agent associated with significant toxicities, most importantly hemorrhagic cystitis. Many approaches including mesna use were established to reduce this toxicity. However, data on mesna efficacy are conflicting. Objective To investigate the incidence of hemorrhagic cystitis in patients receiving cyclophosphamide therapy with or without mesna. Methods A retrospective chart review was done on all adult patients receiving cyclophosphamide therapy with or without mesna at the King Saud University Medical City. The incidence of hemorrhagic cystitis was recorded. Patients receiving mesna were compared with those not receiving mesna. Data were reported as numbers and percentages, and appropriate statistical tests of association were used. This step was followed by a comprehensive literature review using appropriate keywords in PubMed from the inception of the database until August 2019. All studies of interest were reported. Results A total of 718 patients’ medical records were reviewed. The majority of the patients received mesna (n = 433, 60%). The mesna group had a greater incidence of hemorrhagic cystitis (3.5% vs. 0.4%, p < 0.004) and received a significantly larger cumulative dose (3103 ± 1696 vs. 2465 ± 1528, p < 0.001) mg of cyclophosphamide therapy. Our literature review revealed large differences in the conclusions of published trials with highly diverse study designs and populations, emphasizing on the need of large prospective trials to address this topic. Conclusion and relevance: Our study results do not support the use of mesna in preventing hemorrhagic cystitis. We found that the only influential factor in the development of hemorrhagic cystitis was the dose of cyclophosphamide therapy.
