Abstract
PURPOSE: The optimal frequency of monitoring patients with metastatic breast cancer (MBC) is unknown; however, data suggest that intensive monitoring does not improve outcomes. We performed a population-based analysis to evaluate patterns and predictors of extreme use of disease-monitoring tests (serum tumor markers [STMs] and radiographic imaging) among women with MBC. METHODS: The SEER-Medicare database was used to identify women with MBC diagnosed from 2002 to 2011 who underwent disease monitoring. Billing dates of STMs (carcinoembryonic antigen and/or cancer antigen 15-3/cancer antigen 27.29) and imaging tests (computed tomography and/or positron emission tomography) were recorded; if more than one STM or imaging test were completed on the same day, they were counted once. We defined extreme use as > 12 STM and/or more than four radiographic imaging tests in a 12-month period. Multivariable analysis was used to identify factors associated with extreme use. In extreme users, total health care costs and end-of-life health care utilization were compared with the rest of the study population. RESULTS: We identified 2,460 eligible patients. Of these, 924 (37.6%) were extreme users of disease-monitoring tests. Factors significantly associated with extreme use were hormone receptor-negative MBC (odds ratio [OR], 1.63; 95% CI, 1.27 to 2.08), history of a positron emission tomography scan (OR, 2.92; 95% CI, 2.40 to 3.55), and more frequent oncology office visits (OR, 3.14; 95% CI, 2.49 to 3.96). Medical costs per year were 59.2% higher in extreme users. Extreme users were more likely to use emergency department and hospice services at the end of life. CONCLUSION: Despite an unknown clinical benefit, approximately one third of elderly women with MBC were extreme users of disease-monitoring tests. Higher use of disease-monitoring tests was associated with higher total health care costs. Efforts to understand the optimal frequency of monitoring are needed to inform clinical practice.