e22209 Background: The 21-gene recurrence score (RS) assay became commercially available (Oncotype DX) in January 2005. It is used to predict the likelihood of distant recurrence in women with estrogen-receptor (ER)-positive, lymph node-negative invasive breast cancer treated with adjuvant tamoxifen. We aimed to identify clinicopathologic predictors of an elevated recurrence score in a group of women with invasive breast cancer living in a predominantly Hispanic population on the Texas-Mexico border. Methods: A retrospective cohort study of 60 consecutive patients with primary ER-positive, lymph node-negative invasive breast cancer who had an Oncotype DX assay performed by Genomic Health, Inc. on paraffin-embedded tumor between March 2006 and November 2008. ER, PR and HER-2 was performed by immunohistochemistry. Patients were classified as low RS (<18), intermediate RS (18–30), or high RS (≥31). Ordinal logistic regression was used to calculate odds ratios (OR) for an increasing RS. Patient age and tumor pathological features were documented in each group. There was no selection bias in ordering the assay. Results: 95% of the cohort was Hispanic. Average age was 55.5 years. 29 patients (48%) had a low RS, 15 (25%) had an intermediate RS, while 16 (27%) had a high RS. HER-2 was amplified in 8 patients (13%). HER-2 positivity was strongly associated with a high RS (p<0.0001). Tumor grade and Ki-67 proliferative index were correlated with one another in a positive fashion (weighted kappa=0.46, p<0.05) and in univariate analyses both factors were significant predictors of a higher RS: tumor grade 3 vs. 1 OR=26.6 (p<0.0001) and Ki-67 proliferative index high vs. low OR=6.59 (p=0.0033). After adjustment, neither OR was significant. A negative progesterone receptor (PR) status was a strong risk factor for a higher RS (adjusted OR=21.64, p=0.0002). Univariate and multivariate ORs for higher RS for invasive ductal vs. invasive lobular carcinoma were, respectively, 4.3 (p=0.051) and 2.23 (p=0.4). Conclusions: Initially, a tumor grade of 3 and a high Ki-67 proliferative index were strong risk factors for a higher RS. However, after controlling for multiple factors, neither tumor grade nor Ki-67 proliferative index had an impact on RS in this predominantly Hispanic cohort. No significant financial relationships to disclose.
Ki-67 proliferative index correlation to the histo-pathological grade in 300 early breast cancer patients aged < 70 years: A single centre experience