Purpose: The feasibility of Oncotype DX Breast Recurrence Score testing on diagnostic core needle biopsy (CNB) samples has been demonstrated through analysis of a large central laboratory experience. However, concordance with paired samples from the same primary breast tumor has not been comprehensively evaluated. The primary objective of this study was to determine the degree of concordance of Recurrence Score (RS) results between paired CNB and surgical excision (SE) specimens from the same untreated primary breast tumor of patients with early-stage, hormone receptor-positive, human epidermal growth factor receptor 2-negative invasive breast cancer.
Materials and methods: Patients with a clinical RS result on either a CNB or SE specimen were included. Lin concordance correlation coefficient (CCC) with 95% CIs was estimated to assess agreement of continuous RS results between paired samples. Cohen Kappa with 95% CIs was used to evaluate categorical RS result concordance.
Results: A total of 134 patients were identified with paired CNB and SE specimens. The median age was 62 years (range, 33-99; 23 patients [17%] were age ≤50 years v 111 [83%] age >50 years). The mean RS results were 15.6 (range, 0-56) for CNB and 16.6 (range, 0-59) for SE (P = .003), with no statistically significant differences in RS categories. Agreement between continuous RS results from paired samples was strong, with a Lin CCC of 0.86 (95% CI, 0.80 to 0.90). The overall percent agreement in RS categories was 91.8% (95% CI, 87.1 to 96.4). Categorical agreement was further supported by a Cohen Kappa statistic of 0.64 (95% CI, 0.44 to 0.83), indicating substantial agreement between CNB and SE specimens.
Conclusion: The results of this study demonstrate high concordance of RS results between paired samples, which supports the use of CNB for Oncotype DX testing.