48P - Low hormone receptor (HR) status and the benefit of hormonal therapy (HT) in patients with early breast cancer (EBC)

Date 07 May 2015
Event IMPAKT 2015
Session Welcome reception and Poster Walk
Topics Anti-Cancer Agents & Biologic Therapy
Breast Cancer, Early Stage
Biomarkers
Presenter Cristina Guarducci
Citation Annals of Oncology (2015) 26 (suppl_3): 15-24. 10.1093/annonc/mdv117
Authors C. Guarducci1, M. Bonechi1, C. Biagioni2, L. Malorni2, L. Biganzoli2, M.C. Truglia3, S. Vitale2, G. Soldi2, A. Di Leo2, I. Migliaccio1
  • 1Translational Research Unit, Hospital of Prato, Istituto Toscano Tumori, 59100 - Prato/IT
  • 2Medical Oncology Unit, Hospital of Prato, Istituto Toscano Tumori, 59100 - Prato/IT
  • 3Pathology, Hospital of Prato, Istituto Toscano Tumori, 59100 - Prato/IT

Abstract

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Introduction: A cutoff of ≥1% of positive tumor cells is recommended to define estrogen receptor (ER)+ and progesterone receptor (PR)+ tumors and address patients (pts) to HT. However, studies suggest that pts with tumors with low HR levels might have a prognosis similar to pts with HR- tumors. We aim to investigate the clinico-pathological characteristics of tumors with low ER or PR status and to analyze the prognosis and benefit from HT of pts with such tumors.

Material and methods: We retrospectively analyzed 1,922 pts with EBC and complete data on ER status treated at our Institution from 1993 to 2010. Pts were stratified into ER- (ER = 0%), ER low (1% ≤ ER ≤ 10%) and ER high (ER > 10%). ER+ pts were further stratified into PR- (PR = 0%), PR low (1% ≤ PR ≤ 10%), and PR high (PR > 10%). Disease-free survival (DFS) was estimated by Kaplan-Meier survival analysis and compared by log-rank test. Adjusted analysis for node status (N0 vs N + 1-3 vs N + ≥4), adjuvant chemotherapy (Yes vs No) and PR or ER status (negative vs low vs high) was also performed.

Results: 75/1,922 (3.9%) pts had ER low tumors. Compared with ER high pts, ER low pts were less likely to have lobular disease, low Ki67 and small tumors (4% vs 13%; 28% vs 48%; 61% vs 75% respectively), and more likely to have G3 and HER2+ tumors (24% vs 14%; 21% vs 8% respectively). At a median follow-up of 8 years, median DFS was 10 years (95% CI, 8.3-12.3) in the ER- group, 11.1 years (95% CI, 7.3-13.1) in the ER low group, 12.6 years (95% CI, 11.6-14.7) in the ER high group (p < 0.0001). ER low pts who received HT (56/75; 74.6%) had a median DFS significantly longer compared with that of those who did not (11.4 vs 3.4 years respectively, p = 0.0035). Adjusted analysis showed similar results. 178/1,922 (9.3%) pts had ER + /PR low tumors. Among these, pts who were treated with HT (164/178; 92.1%) had a median DFS significantly longer compared with those who were not (11.4 vs 5.5 years respectively, p = .0122). Adjusted analysis results were consistent. Similar results were obtained in the ER low/PR low subgroup (33/1,922; 1.7%).

Conclusions: Our data suggest that ER low tumors have clinico-pathological characteristics and prognosis comparable to ER- tumors. However pts with ER low or ER + /PR low tumors seem to benefit from HT.

Disclosure: L. Malorni: Research grant from Pfizer.

A. Di Leo: Honoraria from AstraZeneca and Novartis, research grant from Pfizer.

All other authors have declared no conflicts of interest.