Health-related quality of life and estimation of the minimally important difference in the Functional Assessment of Cancer Therapy-Endocrine Symptom score in postmenopausal ER+/HER2- metastatic breast cancer with low sensitivity to endocrine therapy

PLoS One. 2022 Nov 29;17(11):e0278344. doi: 10.1371/journal.pone.0278344. eCollection 2022.


Background: The HORSE-BC study previously demonstrated that second-line endocrine therapy (ET) for patients with acquired endocrine-resistant metastatic breast cancer (MBC) still provided a clinically meaningful benefit. Herein, we investigated the health-related quality of life (HRQOL) in the HORSE-BC study.

Methods: Patients with acquired endocrine-resistant MBC who were scheduled for second-line ET were recruited. The HRQOL was assessed at baseline, and 1 and 3 months after second-line ET initiation. To investigate the minimally important difference (MID) in the Functional Assessment of Cancer Therapy-Endocrine Symptoms (FACT-ES), we evaluated the means and standard deviations for the distribution-based method, and differences in the change in HRQOL for the anchor-based method. We also investigated the association between FACT-ES total scores and clinical benefit.

Results: Overall, 56 patients were enrolled. Of these, 47 were analyzed. When defined as 1/3 standard deviation estimates based on the distribution method, the calculated MID was 5.9. The MIDs of the FACT-ES total scores based on the anchor method were 7.7 for decline and 4.1 for improvement. The MID decline proportions were 6.1% and 14.7% lower in patients who experienced clinical benefits than in those who did not at 1 and 3 months, respectively. The ratios of MID improvement in patients who experienced clinical benefits were 18.3% and 3.2% higher, respectively; the mean change in the FACT-ES total score from baseline improved in patients who experienced clinical benefits.

Conclusions: Maintaining the HRQOL as determined by FACT-ES may be associated with clinical benefits in patients with acquired endocrine-resistant MBC treated with ET.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cognition
  • Humans
  • Neoplasms*
  • Postmenopause
  • Quality of Life*

Grants and funding

This study was funded by AstraZeneca. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.