Borderline estrogen receptor-positive breast cancers in black and white women
Menée à partir des données d'une étude portant sur 2 859 patientes atteintes d'un cancer du sein ER+, ER- ou à la limite de surexprimer le récepteur aux estrogènes (ER-borderline), cette étude analyse les caractéristiques génomiques de ces trois types tumoraux, puis évalue pour chacun d'entre eux la survie en fonction de l'origine ethnique des patientes et de l'administration d'un traitement endocrinien
Background : Some breast tumors expressing ≥1% and <10% estrogen receptor (ER) positivity (“ER-borderline”) are clinically aggressive; others exhibit luminal biology. Prior ER-borderline studies included few black participants.
Methods : Using the Carolina Breast Cancer Study (Phase 1: 1993 – 1996, 2: 1996 – 2001, 3: 2008-2013), a population-based study that oversampled black women, we compared ER-borderline (n = 217) to ER-positive (n = 1,885) and ER-negative (n = 757) tumors. PAM50 subtype and risk of recurrence score (ROR-PT, incorporates subtype, proliferation, tumor size) were measured. Relative frequency differences (RFD) were estimated using multivariable linear regression. Disease-free interval (DFI) was evaluated by ER category and endocrine therapy receipt, overall and by race using Kaplan Meier and Cox models. Statistical tests were two-sided.
Results : ER-borderlines were more frequently Basal-like (RFD = +37.7%, 95% CI = 27.1, 48.4) and high ROR-PT (RFD = +52.4%, 95% CI = 36.8, 68.0) relative to ER-positives. Having a high ROR-PT ER-borderline tumor was statistically significantly associated with black race (RFD = +26.2%, 95% CI = 9.0, 43.3). Compared to ER-positives, DFI of ER-borderlines treated with endocrine therapy was poorer but not statistically significantly different (hazard ratio [HR]=2.03, 95% CI = 0.89, 4.65), whereas DFI was statistically significantly worse for ER-borderlines without endocrine therapy (HR = 3.33, 95% CI = 1.84, 6.02). However, black women with ER-borderline had worse DFI compared to ER-positives, even when treated with endocrine therapy (HR = 2.77, 95% CI = 1.09, 7.04).
Conclusions : ER-borderline tumors were genomically heterogeneous with survival outcomes that differed by endocrine therapy receipt and race. Black race predicted high-risk ER-borderlines and may be associated with poorer endocrine therapy response.
Journal of the National Cancer Institute , résumé, 2018