Survey of carboplatin dosing strategies in oncology practices

Objectives: To identify variations in carboplatin dose calculations at oncology institutions and practices in the southeastern United States. Methods: 500 surveys were mailed to oncology practices in the southeastern United States to assess variations in carboplatin doses. The survey sought to determine assumptions that are made regarding carboplatin calculations and if different carboplatin doses result when participants are given the same data and patient characteristics. Results: The survey had a response rate of 12% (n = 56 of 467). The majority of responses used actual serum creatinine and actual body weight. The Cockcroft-Gault creatinine clearance formula was used most commonly. The doses calculated in the case example of an AUC (area under the curve) 6 dose of carboplatin ranged from 110 to 1,811 mg (mean 987 mg, median 963 mg). We determined a correct dose of 721 mg for the case example. Conclusion: The majority of responses to the case example indicated overdosing of carboplatin. Participants provided inconsistent doses, and their interpretation of the variables in the equations varied. More research is needed, and efforts should be made to have a universal modified Calvert formula with standardized assumptions to achieve consistent dosing across practices.