New Endocrine Therapy After Surgery for ER-Positive HER2-Negative Breast Cancer: What the Giredestrant Study Showed

After surgery for early hormone receptor-positive breast cancer, patients are typically prescribed long-term endocrine therapy. This may include tamoxifen, aromatase inhibitors, or their sequential combination. The goal of such treatment is to reduce the risk of recurrence. But even with a properly selected regimen, recurrences still occur, especially in high-risk patients.

In March 2026, results of the phase III lidERA study were presented. It evaluated giredestrant — an oral selective estrogen receptor degrader — as adjuvant therapy in patients with ER-positive HER2-negative early breast cancer. The study enrolled 4,170 patients after surgery with intermediate or high risk of recurrence who had previously received standard endocrine therapy for at least 2 years.

lidERA Study Results

The primary efficacy endpoint was invasive disease-free survival (iDFS). With a median follow-up of approximately 3 years, giredestrant demonstrated a statistically significant 30% reduction in recurrence risk compared with physician's choice endocrine therapy (HR 0.70; 95% CI 0.56–0.88; p=0.0014). Three-year disease-free survival was 92.4% in the giredestrant group versus 89.6% in the control group.

The safety profile of giredestrant was generally manageable. The rate of grade 3 or higher adverse events was comparable to the control group. The most common side effects included arthralgia, hot flashes, and fatigue.

When to Seek a Second Opinion

• you have lymph node involvement or high Ki-67
• you have been on endocrine therapy for more than 2 years and want to understand whether it needs to be changed or extended
• you have a luminal B subtype and want to assess whether your current regimen is sufficient
• significant side effects from endocrine therapy are making it difficult to continue treatment
• you are being offered different options for continuing treatment and need clear decision logic
• you want to assess your individual recurrence risk and understand what new options may be available

What to Prepare Before Your Consultation

For a thorough review, it is best to prepare in advance discharge summaries from all treatment stages, morphological and immunohistochemistry reports (ER, PR, HER2, Ki-67), genetic test results (if performed), description of current endocrine therapy and its tolerability, and recent examination data (mammography, ultrasound, CT).

Conclusion

The lidERA study showed that giredestrant can improve disease-free survival in patients with ER-positive HER2-negative early breast cancer of intermediate and high risk. The drug is not yet approved, but the results already change our understanding of the possibilities of adjuvant endocrine therapy. For patients currently receiving endocrine therapy or planning its extension, this is a reason to discuss their treatment strategy with an oncologist.