Correlation between Nottingham grade and Oncotype DX score in breast cancer: Implications for cost-effective incorporation of oncotype in the clinic.

Abstract

106 Background: Nottingham grading (NG) for breast cancer uses tubule formation (TF), nuclear polymorphism (NP), and mitotic count (MC). The Oncotype Dx recurrence score (RS) is a 21-gene assay that predicts recurrence. Both NG and RS can influence decisions about the use of adjuvant chemotherapy in patients with ER+, HER2-, T1-T2, N0 cancers. The objective was to determine the correlation of overall NG, TF, NP, MC with RS risk group in such patients. This may be useful in guiding the use of Oncotype in specific cases. Methods: 231 patients referred to the BC Cancer Agency between 2007-2011 with ER+, HER2-, T1-T2, N0 breast cancer and an Oncotype were identified. Histologic grading was assessed on the specimen used for Oncotype. Spearman’s correlation coefficients, and 95% confidence intervals (CI) were calculated for the RS risk group versus overall NG, TF, NP, and MC. This study adds to the literature as it is one of the largest cohorts examining this topic and focuses on a HER2- patient population. Results: There was a significant positive moderate correlation between RS and overall grade (Spearman coefficient 0.47, [95%CI: 0.36, 0.56])(Table 1), and RS and MC (Spearman 0.44, [95%CI: 0.33, 0.54]). There was a significant positive weak correlation between RS and TF (Spearman 0.25, [95%CI: 0.13, 0.37]) and RS and NP (Spearman 0.34, [95%CI: 0.22, 0.45]). None of the patients with low overall NG had a high risk RS. Conclusions: Patients with a low NG are unlikely to have a high risk RS (0 in 231 patients) and very few such patients would benefit from the expense of an Oncotype. Overall NG has a better correlation with RS than TF, MC, or NP components alone. [Table: see text]

Prospective Evaluation of the 21-Gene Recurrence Score Assay for Breast Cancer Decision-Making in Ontario

“…Similarly, in a study from British Columbia, no high RS tumors were grade I. 17 In the study by Paik et al, 2 tumor grade was prognostic for distant recurrence and the RS was independently prognostic. Although an association was noted between histologic grade, and RS, only modest agreement existed among three pathologists who assessed the grade centrally.…”