Mammographic Density Decline, Tamoxifen Response, and Prognosis by Molecular Characteristics of ER-Positive Breast Cancer
Menée à partir de données portant sur 215 patientes atteintes d'un cancer du sein ER+ et 62 cas de décès par la maladie, cette étude évalue, en fonction des caractéristiques moléculaires de la tumeur, l'association entre une baisse de la densité mammographique du sein non atteint, la réponse au tamoxifène et le pronostic
Background : Mammographic breast density (MBD) decline post-tamoxifen initiation is a favorable prognostic factor in estrogen receptor (ER)-positive breast cancer (BC) and has potential utility as a biomarker of tamoxifen response. However, the prognostic value of MBD decline may vary by molecular characteristics among ER-positive patients.
Methods : We investigated associations between MBD decline (≥10% vs <10%) and breast cancer-specific mortality (BCSM) among ER-positive breast cancer patients aged 36–87 years at diagnosis treated with tamoxifen at Kaiser Permanente Northwest (1990–2008). Patients who died of BC (cases; n = 62) were compared to those who did not (controls; n = 215) overall and by tumor molecular characteristics [immunohistochemistry(IHC)-based subtype (luminal A-like: ER+/PR+/HER2-/low Ki67; luminal B-like: ER+ and one or more of PR-, HER2+, high Ki67) and modified IHC-based recurrence score of ER/PR/Ki67, ie, mIHC3-score]. Percent MBD was measured in the unaffected breast at baseline mammogram (mean=six months before tamoxifen initiation) and follow-up (mean = 12 months post-tamoxifen initiation). Adjusted odds ratios [ORs] and 95% confidence intervals [CIs] were computed from logistic regression models. All statistical tests were 2-sided.
Results : MBD decline was statistically significantly associated with reduced risk of BCSM overall [OR and 95%CI = 0.38(0.15–0.92)]. This association was, however, stronger among women with aggressive tumor characteristics including luminal B-like [0.17(0.04–0.73)] vs A-like [0.74(0.19–2.92)]; large [0.26(0.08–0.78)] vs small [0.41(0.04–3.79)] tumors; PR– [0.02(0.001–0.37)] vs PR + [0.50(0.18–1.40)] disease; and high [0.25(0.07–0.93)] vs low [0.44(0.10–2.09)] mIHC3-score.
Conclusion : The findings support MBD decline as a prognostic marker of tamoxifen response among patients with aggressive ER-positive BC phenotypes, for whom understanding treatment effectiveness is critical.
JNCI Cancer Spectrum , article en libre accès, 2021