What affects the public healthcare costs of breast cancer in New Zealand?

This study aims to identify the factors that affect the public healthcare costs of stage I-III breast cancer and stage IV cancer in New Zealand. We identified 16,977 stage I-III and 1,093 stage IV breast cancer patients eligible for this study. The costs of stage I-III cancer in the second to fifth year post diagnosis decreased over time, and the costs of stage IV cancer in the first-year post diagnosis increased over time. After adjustment for other factors, the costs of stage I-IV cancer decreased with age but increased with cancer stage. HER2+ cancers had the highest costs, followed by triple negative cancers.. For stage I-III cancers, women living in nonmajor urban areas had a higher chance of incurring costs in follow-up years, and screen detected patients and patients having any services in a private hospital had a decreased probability of receiving any public healthcare services. Pacific women had higher costs than others, but after adjustment for cancer stage, subtype, and other factors, they had lower costs than others. The early detection and better management of stage I-III breast cancer can lead to better outcome and lower costs in follow-up years.