Ross Lawrenson

Backgrounds The pressure to the healthcare system for providing ongoing monitoring and treatment for breast cancer survivors is increasing. 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. Methods We identified women diagnosed with invasive breast cancer between July 1, 2010 and June 30, 2018 and who received services in a public hospital. Patients were identified from the National Breast Cancer Register and/or New Zealand Cancer Registry and were linked to the national administrative datasets. A two‐part model was used to identify the factors that affect the public healthcare costs of stage I–III breast cancer and stage IV cancer. Results 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. After adjustment for other factors, Pacific and Asian women had lower costs, and Māori had similar costs compared to others. 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. Conclusions 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.