The economic burden of metastatic breast cancer in Spain.

Objectives: The study aimed to estimate the burden of metastatic breast cancer (mBC) in Spain over 5 years.

Methods: An incidence-based cost-of-illness model was developed in which a cohort of patients with mBC was followed from the diagnosis of metastatic disease over 5 years or death. Resource use data were collected through a physician survey conducted with 10 clinical experts in Spain. The model distinguished patients according to HER2 and hormonal receptor (HR) status, and followed the patient cohort in monthly cycles.

Results: The incident cohort was estimated to be 2,923 patients with mBC, consisting of 1,575 HER2-/HR+, 520 HER2+/HR+, 324 HER2+/HR-, and 503 triple negative patients. The estimated mean survival over the 5-year time period was 2.51 years, on average, with longer survival of 3.36 years for HER2+/HR+, 2.41 years for HER2-/HR+, 2.82 years for HER2+/HR- and shortest mean survival of 1.74 years for triple negative patients. The total costs were €469,92,731 for the overall population, €190,079,787 for the HER2-/HR+, €151,045,260 for the HER2+/HR+, €80,827,171 for the HER2+/HR- and €47,540,512 for the triple negative subgroups over 5 years. Per patient total costs were €160,642 on average, €120,664 for HER2-/HR+, €290,346 for HER2+/HR+, €249,152 for HER2+/HR-and €94,572 for triple negative patients over 5 years.

Conclusions: The economic burden of mBC in Spain is significant, but differs by HER2 and HR status. HER2-/HR +patients account for the highest burden due to the prevalence of this category, but HER2+/HR +patients have the highest per patient costs.