title: Hormone-receptor expression and activity of trastuzumab with chemotherapy in HER2-positive advanced breast cancer patients.
abstract: BACKGROUND
  The relationship between quantitative immunohistochemical hormone receptor expression and response to the combination of trastuzumab with chemotherapy in HER2-positive advanced breast cancer is currently unknown.
  
  
  METHODS
  Estrogen receptor (ER) and progesterone receptor expression was studied both as a dichotomous variable (positivity set at ≥ 1% of positive cells) and as a continuous variable. The effect of hormone receptor expression on overall response rate and progression-free survival in patients receiving trastuzumab-based treatment was studied by univariate and multivariate analysis.
  
  
  RESULTS
  One hundred eleven of 227 consecutive advanced breast cancer patients treated at 2 Institutions had hormone receptor-positive tumors (49%). High expression of ER (≥ 30% of tumor cells) predicted reduced probability of tumor response to trastuzumab plus chemotherapy (multivariate odds ratio, 0.422; 95% confidence interval [CI], 0.222-0.803; P = .009). In patients with hormone receptor-positive tumors (≥ 1% of tumor cells), maintenance endocrine therapy added to trastuzumab upon the completion of chemotherapy was associated with a significant progression-free survival benefit (hazard ratio, 0.521; 95% CI, 0.3325-0.836; P = .007).
  
  
  CONCLUSIONS
  Our results suggest a predictive role of hormone receptor expression in HER2-positive tumors. Further investigation in this patient subset is warranted to optimize the use of HER2-targeting agents, chemotherapy, and endocrine therapy.
authors: Division of Medical Oncology 1, Piedmont Foundation for Oncology, Institute for Cancer Research and Treatment, Candiolo, Italy. filippo.montemurro@ircc.it
authors: Filippo
authors: F
authors: Montemurro
authors: Valentina
authors: V
authors: Rossi
authors: Maria
authors: M
authors: Cossu Rocca
authors: Rossella
authors: R
authors: Martinello
authors: Elena
authors: E
authors: Verri
authors: Stefania
authors: S
authors: Redana
authors: Laura
authors: L
authors: Adamoli
authors: Giorgio
authors: G
authors: Valabrega
authors: Anna
authors: A
authors: Sapino
authors: Massimo
authors: M
authors: Aglietta
authors: Giuseppe
authors: G
authors: Viale
authors: Aron
authors: A
authors: Goldhirsch
authors: Franco
authors: F
authors: Nolè