We test the robustness of our algorithm by varying the presence of other hormonal receptors (PR, human epidermal growth factor), tumor grade, tumor origin location (ductal, lobular), as well as demographic variables (menopause, race), and find that other receptors and tumor grade can significantly influence classifier predictions, while the location of cancer origin and demographic variables considered do not. The gene discussed is NR4A1; the disease is neoplasm.