Comparison of Magee and Oncotype DX Recurrence Scores in estrogen receptor positive breast cancers

Data from pathology reports of estrogen receptor positive (ER+) breast cancers with Ki67 < 14% (luminal-A; n = 128) and Ki67 >= 14% (luminal-B; n = 100) were entered into the automatic recurrence score (RS) calculator accessible at the University of Pittsburgh Department of Pathology website. Using RS obtained with Magee equations #1 and #3, an average modified Magee recurrence score (AMM RS) was calculated for each tumor. The AMM RS and the Oncotype DX RS (Onco RS) were compared per tumor and associated with follow-up. AMM RS and Onco RS agreed in 64.9% (148 of 228) breast cancers (70.3% luminal-A and 58% luminal-B). There was only one two-step (low risk by Onco/high risk by AMM) RS disagreement. This luminal-B patient is alive without recurrence and free of tumor at 46 months postdiagnosis. Low-risk/intermediate-risk disagreements comprised 94.7% (36 of 38) and 69% (29 of 42) of the RS disagreements in the luminal-A and luminal-B groups, respectively (P = 0.004). In luminal-A, there were only two intermediate/high-risk disagreements; both high-risk ratings were by Onco RS. In luminal-B, there were 12 intermediate/high-risk disagreements; 11 of the high-risk ratings were by Onco RS. 100% (3 of 3) luminal-A tumors and 75% (6 of 8) luminal-B tumors that were high risk by AMM RS were also high risk by Onco RS. Eight tumors recurred and/or metastasized. AMM RS and Onco RS disagreed in only two of these eight tumors. The high percentage of tumors scored as intermediate risk (50% by AMM RS and 39% by Onco RS) is a major limitation of both scoring algorithms.