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Biomarker Concordance of Invasive Breast Carcinoma on Re-Evaluation: A Comprehensive Retrospective Real-World
Pooja Padwale1, Ayushi Sahay1, Archita Juneja1
1Department of Pathology, Tata Memorial Centre and Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Homi Bhabha National Institute (HBNI), Parel, Mumbai, India.
Purpose:
Biomarkers estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) may undergo alteration on reassessment, with significant impact on management. There is a paucity of large-scale paired data on biomarker changes from low- and middle-income countries (LMICs).
Materials And Methods:
We performed a retrospective audit on 1,107 paired samples, wherein biomarkers were performed at least twice between: core needle biopsy (CNB) and upfront resection (category 1, n = 277); CNB and postchemotherapy resection (category 2, n = 104); primary (CNB/resection) and recurrence (local/metastatic; category 3, n = 702); and initial and subsequent distant metastasis (category 4, n = 24). Concordance was noted for individual receptors and surrogate molecular classification (hormone receptor+HER2-, hormonal receptor+HER2+, hormonal receptor-HER2+, triple-negative).
Results:
Overall concordance for ER, PR, and HER2 was 85.4% (k value = 0.693), 77.1% (k value = 0.541), and 93.8% (k value = 0.827), respectively. For HRs, higher concordance was in category 1 > 3 > 2 > 4 (ER k value = 0.764 > 0.684 > 0.591 > 0.515, respectively; PR k value = 0.68 > 0.495 > 0.482 > 0.329, respectively), while HER2 was relatively constant across categories (k value range, 0.808-0.882). Molecular classification showed overall 79.5% concordance (k value = 0.688). Discordance was 27.1% in triple-positive (highest) and 17.7% in HER2+/hormonal receptor- (lowest). Univariate and multivariate analyses showed poorer concordance for therapy (v no therapy; odds ratio [OR], 0.437 [95% CI, 0.255 to 0.749]; P = .003) and specific/targeted therapy (v CT alone; OR, 0.126 [95% CI, 0.073 to 0.217]; P = .001). Shorter time interval (<6 months), both specimens breast, CNB, and optimum fixation showed better concordance on univariate (P = .004, .002, .01, and .009, respectively) but not multivariate analysis.
Conclusion:
Biomarker re-evaluation is not mandatory between CNB and upfront resection or evaluating HER2 status alone, but one in five patients may show discordance at metastasis/recurrence. We recommend re-evaluation in recurrent/metastatic settings, post-treatment, >6 months' time interval, or poorly fixed material, which is of particular relevance in LMICs.
