Abstract P6-08-46: Clinical outcomes of breast cancer patients with intermediate oncotype DX recurrence scores (RS): A review of the Cleveland Clinic Experience

Background: The 21 gene RT-PCR assay (Oncotype Dx, Genomic Health, Inc, Redwood City, CA) performed on formalin-fixed paraffin-embedded tissue quantifies the likelihood of distant recurrence in patients with estrogen receptor (ER)-positive, axillary lymph node-negative breast cancer. The 21 gene recurrence score (RS) also quantifies the magnitude of clinical benefit of adjuvant cytotoxic chemotherapy to endocrine therapy. Patients with a high risk RS clearly benefit from the addition of adjuvant chemotherapy, while patients with a low RS do not. However, approximately one-third of patients have an intermediate RS (18-31) and the incremental benefit from adjuvant chemotherapy is unclear. The primary objective of this study was to evaluate the clinical outcomes of early stage breast cancer patients with intermediate RS. Methods: We identified 262 patients with intermediate RS (18-31) in a prospectively maintained registry of patients with Oncotype Dx testing at the Cleveland Clinic from 2004-2013. ER status, progesterone receptor (PR) status, HER2 gene amplification, treatment with chemotherapy, follow-up for distant recurrences and other clinical and pathological variables were collected for all patients in the registry. Results: Patient characteristics are listed in Table 1. One hundred patients (38.2 %) were treated with chemotherapy plus endocrine therapy, while 156 (59.5%) were treated with endocrine therapy alone. Treatment data was unavailable for 6 patients (2%). Distant recurrence status is unknown for 2 patients. The overall rate of distant plus local recurrence for all 262 patients was 3.8% (3 local and 7 distant recurrences). There were 6 and 4 recurrences respectively, for patients received chemotherapy plus endocrine therapy (6%), and in patients treated with endocrine therapy alone (2.5%), which was not significantly different (p=.21). Conclusions: With a median follow-up of 45 months, our data indicate that the realized distant recurrence rate for patients with an intermediate range RS was less than 5%. These data do not exclude the possibility that some patients with an intermediate RS may derive a small incremental benefit from the addition of adjuvant chemotherapy. Larger, randomized prospective trials like TAILORx should provide additional guidance for the management of this patient population. Citation Format: Lindsey M Goodman, Alberto J Montero, Lisa Rybicki, Karen Mrazeck, Benjamin Calhoun, Raymond Tubbs, Halle Moore. Clinical outcomes of breast cancer patients with intermediate oncotype DX recurrence scores (RS): A review of the Cleveland Clinic Experience [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-08-46.