Differences in Breast Cancer Costs by Cancer Stage and Biomarker Subtype in New Zealand

Background Breast cancer requires the greatest expenditure among all cancer types, and the costs vary by cancer stage and biomarker status. Objective This study aimed to examine the differences in public healthcare costs of breast cancer in New Zealand by stage and subtype. Method This study included patients diagnosed with invasive breast cancer between 1 July 2010 and 30 June 2018 and receiving services in public hospitals. These patients were identified from the National Breast Cancer Register and/or New Zealand Cancer Registry. Linking with the Pharmaceutical Collection, National Minimum Dataset, National Non-Admitted Patient Collection, and Mortality Collection, we estimated the median public healthcare costs of breast cancer by cancer stage and biomarker subtype. Results We identified 22,948 eligible patients. The median costs of breast cancer increased with stage of disease, from $NZ26,930 for stage I disease to $NZ50,388 for stage IV disease. The median costs for human epidermal growth factor receptor 2-positive (HER2+) disease were three times those for HER2-negative (HER2−) disease: $NZ106,428 for HER2+ cancers compared with$NZ28,481 for oestrogen receptor-positive (ER+)/HER2− cancers and $NZ31,722 for triple negative disease. Over 55% of the costs for HER2+ breast cancers were targeted therapy costs. For HER2− cancers, surgery incurred the biggest cost, followed by radiotherapy. Conclusions Treating patients with early-stage breast cancer is less costly than treating those with metastatic disease. The costs vary considerably between the subtypes. Patients with HER2+ cancer incurred three times the costs of those with HER2− cancers. These results provide baseline costing data for clinicians and policy makers when considering new targeted treatments.