Optimal adjuvant endocrine treatment of ER+/HER2+ breast cancer patients by age at diagnosis: A population-based cohort study

Eur J Cancer. 2018 Feb:90:92-101. doi: 10.1016/j.ejca.2017.11.010. Epub 2017 Dec 21.

Abstract

Background: Prior randomised controlled trials on adjuvant hormonal therapy included HER2any patients; however, a differential effect of aromatase inhibitors (AIs) versus tamoxifen (TAM) may have been missed in ER+/HER2+ patients that comprise 7-15% of all breast cancer patients. In addition, a woman's hormonal microenvironment may influence sensitivity to TAM and AIs in the adjuvant setting, which changes during menopausal transition, a process that takes years. We studied the efficacy of AIs versus TAM in ER+/HER2+ breast cancer patients grouped by age at diagnosis as a proxy for menopausal status using treatment and outcome data from the nationwide population-based Netherlands Cancer Registry (NCR).

Patients and methods: All women diagnosed between 2005 and 2007 with endocrine-treated, TanyNanyM0, ER+/HER2+ breast cancer were identified through the NCR (n = 1155). Patients were divided by age at diagnosis: premenopausal (≤45 years; n = 326), perimenopausal (45<years≤55; n = 304) and postmenopausal (>55 years; n = 525). A time-dependent variable, indicating whether AI or TAM was received for >50% of endocrine treatment duration, was applied to subdivide groups by predominant treatment received. Recurrence-free survival (RFS) and overall survival (OS) were assessed using Kaplan-Meier survival estimation and Cox regression. Hazard ratios (HRs) were adjusted for chemotherapy, trastuzumab, age at diagnosis, N-status, grade, pT-stage and ovarian ablation.

Results: During follow-up, 237 recurrences and 182 deaths occurred. Perimenopausal women derived significant RFS and OS benefit from AI compared with TAM, HR 0.47 (95% CI 0.25-0.91; P = 0.03) and HR 0.37 (95% CI 0.18-0.79; P = 0.01), respectively, whereas premenopausal women derived no benefit from AI compared with TAM. Treatment effects differed significantly between these age groups (interaction P = 0.03 and P = 0.02, respectively). Among postmenopausal women a small but non-significant AI benefit was observed.

Conclusion: AI treatment, preferably without any TAM treatment, was associated with the best RFS and OS outcome in ER+/HER2+ perimenopausal breast cancer patients.

Keywords: Breast cancer; ER; Endocrine treatment; HER2; Survival analysis; Time-dependent analysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age of Onset
  • Aged
  • Antineoplastic Agents, Hormonal / therapeutic use*
  • Aromatase Inhibitors / therapeutic use*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / mortality
  • Chemotherapy, Adjuvant / methods*
  • Cohort Studies
  • Disease-Free Survival
  • Female
  • Humans
  • Kaplan-Meier Estimate
  • Middle Aged
  • Netherlands
  • Proportional Hazards Models
  • Receptor, ErbB-2 / biosynthesis
  • Receptors, Estrogen / biosynthesis
  • Tamoxifen / therapeutic use*

Substances

  • Antineoplastic Agents, Hormonal
  • Aromatase Inhibitors
  • Receptors, Estrogen
  • Tamoxifen
  • ERBB2 protein, human
  • Receptor, ErbB-2