The effects of Oncotype DX recurrence scores on chemotherapy receipt in a multi-institutional breast cancer cohort.

Abstract

669 Background: The use of traditional clinicopathologic features in decision making in early stage estrogen receptor (ER)-positive breast cancer (BC) may lead to over or under treatment. We investigated the effect of the Oncotype Dx (ODX) genomic profile on receipt of chemotherapy (CTX) in two tertiary cancer centers. Methods: 276 cases of node-negative ER positive BC from two tertiary cancer centers had ODX performed on tumor blocks between 2005 and 2009. Age at diagnosis, tumor size, grade, histology, presence of lymphovascular invasion, and PR status were abstracted from records and provided to 2 medical oncologists specializing in breast cancer. The Adjuvant! Online (AO) relapse risk and the Nottingham Prognostic index (NPI) were calculated. Results: Median age was 55 years (range, 29-82). 13% of patients had a negative PR status. Mean tumor size was 1.58 cm. Fifty percent had grade 2 BC, 38% and 12% were grade 1 and 3. The median 10 year AO relapse risk was 23 (range, 13-60). The median NPI was 3.4 with 80% of patients in the excellent or good category. The median ODX recurrence score was 17. 51%, 40%, and 9% of patients were in the low, intermediate, and high risk categories respectively. Prior to obtaining ODX, medical oncologists were more likely to recommend CTX to women who were younger (p < 0.0001), had negative PR status (p < 0.0001), higher NPI (p < 0.012), and tumors greater than 1 cm (p < 0.015). The average tumor size of patients recommended CTX was 2.0 cm versus 1.2 cm in the group not recommended CTX. The mean AO for those recommended CTX was 28.6 versus 18.9 for those not recommended CTX. ODX resulted in a change in management for 38% of individuals. Of 188 total patients who ultimately DID NOT receive CTX, 71 of them had an initial CTX recommendation. Of 88 patients who DID receive CTX, 34 of them did not have an initial recommendation. CTX was administered to 13/142 patients with low ODX, 52/110 with intermediate ODX, and 23/24 with high ODX. Only 3/24 women with high-risk ODX did not have an initial CTX recommendation. Conclusions: In our multi-institutional cohort, the ODX score had a significant impact on adjuvant chemotherapy decisions. No significant financial relationships to disclose.