296P - HER2-positive early breast cancer in the pre-trastuzumab and trastuzumab eras: A triple positive subgroup analysis of a multicenter retrospective s...

Date 29 September 2014
Event ESMO 2014
Session Poster Display session
Topics Anti-Cancer Agents & Biologic Therapy
Breast Cancer, Early Stage
Pathology/Molecular Biology
Presenter Laura Pizzuti
Citation Annals of Oncology (2014) 25 (suppl_4): iv85-iv109. 10.1093/annonc/mdu327
Authors L. Pizzuti1, C. Natoli2, T. Gamucci3, D. Sergi4, L. Di Lauro4, L. Moscetti5, L. Mentuccia3, A. Vaccaro3, P. Trenta6, P. Seminara7, I.G. Rapposelli2, D. Santini8, V. Sini9, I. Sperduti10, P. Marchetti9, P. Vici4
  • 1Division Of Medical Oncology B, Regina Elena National Cancer Institute, 00144 - Rome/IT
  • 2Department Of Experimental And Clinical Sciences, University "G. d'Annunzio", Chieti/IT
  • 3Department Of Oncology, “S.S. Trinita′” Hospital, Sora/IT
  • 4Division Of Medical Oncology B, Regina Elena National Cancer Institute, Rome/IT
  • 5Division Of Medical Oncology, Belcolle Hospital, ASL di Viterbo Oncology Unit, Viterbo/IT
  • 6Department Of Radiology, Oncology And Human Pathology, Sapienza University of Rome, Rome/IT
  • 7Department Of Experimental Medicine, Sapienza University of Rome, Rome/IT
  • 8Medical Oncology, University Campus Bio-Medico of Rome, Rome/IT
  • 9Oncology Unit, Sant’Andrea Hospital, Sapienza University of Rome, Rome/IT
  • 10Biostatistics Unit, Regina Elena National Cancer Institute, Rome/IT

Abstract

Aim

HER2-positive (HER2+) breast cancer (BC) is a heterogeneous disease, with a minority of patients presenting an excellent prognosis. Recent findings suggest that the efficacy of HER2-directed therapy may differ according to hormone receptor (HR) status, and this raised the question if HR status defines different subtypes of HER2+ BC. We conducted a multicenter analysis of HER2+ early BC patients to determine relapse free survival (RFS) and overall survival (OS), and to investigate the role of HR in outcome.

Methods

We retrospectively enrolled HER2+ (IHC 3+ or 2+ amplified) early BC patients treated with adjuvant chemotherapy with or without trastuzumab (T) in 7 Italian oncologic centres until December 2011. A review of clinical and treatment data was carried out for analysis.

Results

769 chemotherapy-treated HER2+ early BC patients have been analysed and divided into two groups, T-untreated (N = 304, cohort A), and T-treated (N = 465, cohort B). Overall, the median follow-up was 68 months (range, 1-171). Three-year RFS for cohort A was 81.3%, whereas it was 92% for cohort B (p <0.0001). Five-year OS was 88.4% and 95.8% for the cohort A and B, respectively (p = 0.0001). At multivariate analysis, in the whole population, factors related to absence of relapse were older age, earlier stage, T therapy and hormonal treatment. HR-negative disease had a trend, although not significant (p = 0.6), towards a worse 3-year RFS with respect to HR-positive disease. Overall, 356 patients have triple (ER, PgR, HER2) positive (TP) tumors, 132 in the cohort A and 224 in the cohort B, and all underwent also endocrine adjuvant treatment. Three-year RFS for TP patients was 84.6% in the cohort A and 93.7% in the cohort B (p = 0.002). Considering only TP patients with ER staining in 50% or more cancer cells (TP50), 3-year RFS was 90.6% in the cohort A and 93.3% in the cohort B (p = 0.03). Thus, in TP50-patients, addition of T to therapy provides only slight RFS benefit, suggesting a very favourable prognosis.

Conclusions

Although the benefit given by addition of T to adjuvant chemotherapy is clear in all subgroups analyzed, our data suggest the existence of a subset of TP BC, characterized by high levels of ER expression, that is driven both by HER2 and ER signalling, with a biological behaviour similar to ER-positive, HER2-negative BC.

Disclosure

All authors have declared no conflicts of interest.