Enhancing healthcare economics: the impact of manual dose rounding on T-DM1 costs in breast cancer treatment

Introduction: Breast cancer is the second most common cancer worldwide, with HER2-positive disease being an aggressive subtype. Trastuzumab emtansine (T-DM1) has been the gold standard for second-line treatment in HER2-positive metastatic breast cancer since 2012. However, the high cost of cancer treatments presents a significant economic burden. Many oncology drugs, including T-DM1, are dosed on the basis of patient weight, leading to drug wastage due to single-dose vials. Objective: The aim of the study was to determine whether manual dose rounding down can reduce drug wastage and costs. Methods: This retrospective study included patients treated with T-DM1 from January 2015 to December 2022 at the Tampere University Hospital in Finland. Data were collected from chemotherapy and pharmacy software. Drug wastage and cost savings were analyzed. Results: A total of 1797 T-DM1 doses were used over the 8-year study period. The proportion of T-DM1 doses suitable for rounding was on average 67%. Oncologists reduced 31,268 mg of drug waste (74% of total waste) by rounding doses down to the nearest vial size. During the study period, dose rounding resulted in savings of 1,307,659€ (14% of total costs). An additional 609,028€ could have been saved if all possible doses had been rounded down. Conclusions: Manual dose rounding of T-DM1 by oncologists considerably reduced drug wastage and costs. Implementing an automated dose rounding system in the chemotherapy management software would further reduce costs. These findings highlight the importance of innovative healthcare solutions to address the high costs of cancer treatments.