Using the Modified Magee Equation to Identify Patients Unlikely to Benefit From the 21-Gene Recurrence Score Assay (Oncotype DX Assay)

Abstract

Objectives: This study aimed to compare a modified Magee equation with Oncotype DX (Genomic Health, Redwood City, CA) recurrence score (RS) and identify patients who are unlikely to benefit from Oncotype DX.

Methods: Magee equation RS was calculated in 438 cases and correlated with Oncotype DX RS.

Results: The Pearson correlation coefficient ( r ) for the Magee equation and Oncotype DX RS was 0.6645 ( P < .00001), and the overall agreement was 66.4%. All cases (11.6%) with a Magee equation RS greater than 30 or 11 or less had been correctly predicted to have either high Oncotype DX RS or low Oncotype DX RS, respectively.

Conclusions: The modified Magee equation is able to identify up to 12% patients who are unlikely to benefit from Oncotype DX testing. Using the modified Magee equation RS on these patients would be an alternative to Oncotype DX, leading to cost savings.

Keywords: Breast cancer; Estrogen receptor; Magee equation; Oncotype DX; Recurrence score.