Type of estrogen receptor determines response to antiestrogen therapy

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Updated: Nov 4, 2026

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells
16:24

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells

Published on: February 21, 2014

E Villa1, A Dugani, E Fantoni

  • 1Department of Internal Medicine, University of Modena, Italy.

Cancer Research
|September 1, 1996
PubMed

Insights

Tamoxifen treatment failure in liver cancer (HCC) may stem from variant estrogen receptors (ERs). Tailoring antihormonal therapy based on ER type significantly improves patient outcomes.

Area of Science:

  • Oncology
  • Endocrinology
  • Molecular Biology

Background:

  • Unresectable hepatocellular carcinomas (HCCs) often exhibit resistance to tamoxifen therapy.
  • This resistance may be linked to the presence of variant estrogen receptors (ERs) within the tumor cells.

Purpose of the Study:

  • To investigate the impact of variant ER transcripts on HCC growth rates.
  • To evaluate the efficacy of tamoxifen versus megestrol based on ER transcript type in HCC patients.

Main Methods:

  • Patients with unresectable HCC received either tamoxifen (80 mg/day) or megestrol (160 mg/day).
  • Treatment assignment was determined by the presence of wild-type or exon 5-deleted variant ER transcripts.
  • Tumor growth was monitored using magnetic resonance imaging (MRI).

Main Results:

  • HCCs with variant ER transcripts showed a 4-fold increase in growth rate compared to those with wild-type ERs.
  • All patients with wild-type ERs experienced a 50% reduction in tumor volume after 9 months of tamoxifen.
  • Megestrol slowed tumor growth in patients with variant ERs but did not achieve tumor volume reduction.

Conclusions:

  • Personalizing antihormonal therapy based on ER transcript status (wild-type vs. variant) enhances tamoxifen response rates in HCC.
  • While tamoxifen is effective for wild-type ER HCCs, megestrol offers only temporary growth inhibition for variant ER HCCs.

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