Progesterone Receptor (PR) Status and Tumor Grade – Key Factors in Predicting Oncotype DX Results.
Steven Frame, Meredith Burge, Patrick McGrath, Heather Wright, Edward Romond, Marie-Louise Fjallskog, Luis Samayoa. University of Kentucky, Lexington; VAMC, Lexington, KY; Uppsala University, Sweden; Instituto Internacional de Cancer, San Salvador, El Salvador
Background: Oncotype DX is recommended for all node negative (-), Her-2neu (-), Estrogen Receptor (ER) positive (+) breast cancer patients. Using the same parameters as established by this test, our study identifies patients in which equivalent information can be obtained without performing Oncotype DX, thereby optimizing the cost effectiveness of the test.
Design: Recurrence Scores (RS) from 93 patients were correlated with tumor size, tumor grade (G) and PR status. Patients were then grouped in to low, intermediate and high risk categories. We calculated the mean RS and percentage of patients in each risk category for GI, GII and GIII tumors. This data was submitted for statistical analyses using the Fisher exact test. Tumor grade was calculated using the modified Bloom Richardson score system. ER and PR status was determined by Immunohistochemistry (IHC) using appropriate controls. All patients sent for Oncotype DX were pre-screened for strong ER positivity (> 70% of tumor cells) and PR positivity (> 1% of tumor cells).
Conclusions: This analysis validates previous studies stressing the value of PR status in ER (+), node and Her-2neu (-) patients and shows that G and PR status are reliable predictors of RS Oncotype DX results (p<0.01 for all risk categories). The data suggests that Oncotype DX results may not be as useful in patients with G I tumors regardless of their PR status (mean RS of 16) and in PR (-) patients with G III tumors (mean RS of 45). These results could translate into a 20% reduction ($73,935) in the number of tests needed.
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 6, Wednesday Morning