Anxiety, Culture, and Expectations: Oncologist-Perceived Factors Associated With Use of Nonrecommended Serum Tumor Marker Tests for Surveillance of Early-Stage Breast Cancer

Purpose:Breast cancer offers several opportunities for reducing use of ineffective practices based on American Society of Clinical Oncology guidelines. We assessed oncologist-perceived factors associated with use of one such practice—serum tumor markers for post-treatment breast cancer surveillance—focusing on medical oncologists with high, medium, or low test use.Methods:Using a mixed-methods design, we identified patients who had been treated for early-stage breast cancer diagnosed between January 1, 2009, and December 31, 2012, within Kaiser Permanente Southern California and calculated the number of tests ordered from January 1, 2010, to December 31, 2014. We identified oncologists with high, medium, or low use and subsequently performed semistructured interviews. We used patient satisfaction data to assess association between pattern of use and satisfaction score.Results:We identified 7,363 patients, with 40,114 tests ordered. High-use oncologists were defined as those ordering at least one test annu...