[344] The Relationship between Recurrence Score of 21-Gene Assay and Clinicopathological Factors of Breast Cancer

K Woolf, J Wang, DG Hicks, X Wang, LM Schiffhauer, K Skinner, P Tang. University of Rochester Medical Center, Rochester, NY; RTI Health Solutions, Research Triangle Park, NC

Background: Oncotype DX has been increasingly used to aid adjuvant treatment decisions in breast cancer management. In the current study, we sought to investigate the relationship between Oncotype DX recurrence scores (RS) and clinicopathological features in invasive breast carcinomas.
Design: We identified 100 infiltrating carcinomas (91 IDC and 9 ILC) that had Oncotype DX performed from our departmental file and analyzed the relationship between RS and clinicopathological factors. Histologic grades were defined by a consensus results from our breast pathologist group, 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. Ki-67 was recorded as % of nuclear stain. The definitions for each molecular subtype were based on the expression of ER, HER2, EGFR and CK5/6.
Results: Among the 100 cases, 60, 34 and 6 cases belonged to low, intermediate, high risk group, respectively. All tumors in low RS group fell into grades 1-2 tumor; while grade 3 tumors with a RS ranging between 20-54. The p-value for tubule formation, nuclear pleomorphism, and mitosis were 0.1412, 0.1209, and 0.1178, respectively. The mean Allred scores for PR were significantly different (p=0.0003) among low, intermediate, and high RS groups, 7.58, 6.65 and 2.22, respectively. Tumors with a PR Allred score 4 or less had RS approaching or in intermediate or high risk groups (between 16 and 54), Tumors with a 2+(confirmed by FISH) or 3+ of HER2 level had RS between 23 and 54, and with a p-value of 0.0320. 100%, 91% and 50% of low, intermediate, and high RS groups belonged to Luminal A subtype (ER+, HER2-). Ki-67 was not significantly different among these 3 groups (10.83%, 15.03% and 7.33%, respectively), so did patient age (56.27, 53.29 and 60.33, respectively) and tumor size (1.84cm, 2.01cm and 1.42cm, respectively).
Conclusions: Nottingham grade, expression of PR and HER2 should be taken into consideration when choose cases for 21-gene assay in ER positive tumors. Tumors that are grade 3, PR Allred score 4 or less, and HER2 2+ or 3+ are likely to have a higher RS, and may not be needed for 21-gene assay testing.
Category: Breast

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 27, Tuesday Afternoon


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