[311] The Relationship between Oncotype DX Recurrence Score, Clinicopathological Factors, and Molecular Classification in Breast Cancer

P Tang, J Wang, DG Hicks, X Wang, L Schiffhauer, M Shayne, A Huston, K Skinner, J Griggs, G Lyman. University of Rochester Medical Center, Rochester, NY; RTI Health Solution, Research Triangle Park, NC; University of Michigan Medical Center, Ann Arbor, MI; Duke University Medical Center, Durham, NC

Background: Oncotype DX has been increasingly used to aid adjuvant treatment decisions in breast cancer management. In current study, we sought to investigate the relationship between Oncotype DX recurrence scores (RS), clinicopathological features, and molecular classification in invasive breast carcinomas.
Design: We identified 51 infiltrating carcinomas (48 IDC and 3 ILC) from our departmental file and analyzed the relationship between RS and clinicopathological factors. ER and PR were recorded as Allred scores. HER2 was scored as positive if >30% of tumor cells showed 3+ membrane staining. EGFR was designated as positive if any tumor cells showed 1+ positive stain. Any strong cytoplasmic stain was considered as positive for CK5/6. The definitions for each molecular subtype as follws: Luminal A--ER+, HER2-, EGFR and CK5/6+/-; Luminal B--ER+, HER2+, EGFR and CK5/6 +/-; HER2--ER+, HER2+, EGFR and CK5/6 +/-; Basal-like--ER-, HER2-, EGFR and/or CK5/6 +; unclassified --all 4 markers neggative.
Results: Among the 51 cases, 29 had low RS (0-17), 19 had intermediate RS (18-30), and 3 had high RS (>31). PR expression was inversely associated with RS (mean Allred scores =7.76, 6.47 and 2.00 in low, intermediate and high RS group; p=0.0008). Nuclear grade was also associated with RS: 96.5% of the low and 89.5% of the intermediate RS groups were grades 1 and 2, while 100% of the high RS group was grade 3 (p=0.0238). Of the three HER2 positive cases, one was in the intermediate RS group and two were in the high RS group. EGFR and CK5/6 were negative in all cases. All 29 cases of the low RS group belonged to luminal A subtype; 18 of the intermediate RS group were Luminal A, and 1 was luminal B; 3 high RS cases had 2 in Luminal B subtype and 1 in unclassified subtype. Patients' age, tumor size, presence of DCIS, mitosis, and expression of ER and Ki-67 did not show correlation with RS.
Conclusions: PR negativity is strongly correlated with a higher RS score, as well as HER2 over expression and Luminal B subtype, while the luminal A subgroup is associated with a lower RS score. More studies are needed to further investigate these relationships.
Category: Breast

Tuesday, March 10, 2009 8:15 AM

Platform Session: Section B, Tuesday Morning