32 Background: The Oncotype DX (ODX) multigene assay has been previously suggested to result in an overall reduction in the use of adjuvant chemotherapy and associated costs for women with early stage, estrogen receptor (ER)-positive breast cancer. However, the association between adoption of ODX and chemotherapy costs has only previously been considered in theoretical models and has not been examined using actual patient outcomes in real world clinical practice. Methods: Retrospective analysis of Surveillance, Epidemiology, and End Results (SEER) -Medicare data of the association between overall and chemotherapy-specific costs associated with adoption of ODX testing in patients diagnosed with invasive, non-metastatic, ER-positive breast cancer between 2005 and 2009. We limited our primary analysis to women ages 66 to75 to include women in which adjuvant chemotherapy would be most likely to be considered. Total Medicare payments were used to calculate direct costs in the year following diagnosis. NCCN guidelines were used to stratify patients on the basis of clinical and pathologic features into low ( < 1.0 cm), intermediate, and high risk (node positive) disease. Results: A total of 21,272 women met study criteria. Average costs in the year following diagnosis were $31,532 in the overall cohort, and was highest for women with NCCN high risk ($45,192) vs. intermediate ($28,642) or low ($23,662) risk disease. Chemotherapy costs followed similar trends ($4,819, $1,157, and $226 respectively). In multivariable analyses, ODX was associated with a relative decrease in chemotherapy costs among high risk women (RR 0.54, 0.37-0.77), but increased costs among low and intermediate risk women (RR1.36, 1.13-1.26 and RR 3.73, 2.13-56.54). Women with high risk disease had significantly lower absolute chemotherapy costs associated with receipt of ODX (-$2,298, -$3,049 to -$1,547; All P < 0.001). Conclusions: Receipt of ODX testing was associated with relative and absolute decreases in chemotherapy costs, but only in women with high NCCN risk disease. Further research is needed to disentangle correlative vs. causative association of ODX testing with patient outcomes and costs.
Should decisions on adding adjuvant chemotherapy in early-stage ER-positive breast cancer be based on gene expression testing or clinicopathologic factors or both?
