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. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s41669-022-00327-5.