<p><b>OBJECTIVE:</b> To investigate, within a private health insurance, the ordering frequency and the costs related to inappropriate tumor markers test orders. <br> <b>METHODS:</b> This study analyzed data regarding tumor markers requests within a private health insurance between 2010 and 2017. Patients included in this analysis were ≥ 50 years old, had available medical records, and had at least 1 tumor ma...