# Hellenic Cooperative Oncology Group: Observational study in ESR1 Gene Mutation, Breast Cancer (Locally Advanced or Metastatic) (500 participants)

**Score:** 55/100

| Field | Value |
|---|---|
| Sponsor | Hellenic Cooperative Oncology Group |
| Sponsor type | Academic and hospital |
| Study | ESR1 Mutations in Metastatic Hormone Receptor-Positive Breast Cancer in the Greek Population |
| NCT ID | NCT07899463 |
| Phase | Observational |
| Status | recruiting |
| Conditions | ESR1 Gene Mutation; Breast Cancer (Locally Advanced or Metastatic); Hormon Receptor Positive Breast Cancer |
| Target enrollment | 500 |
| Site countries | Greece |
| Posted | 2026-10-27 |
| Planned start | 2025-05-13 |
| Event | Newly registered study |
| Event date | 2026-10-27 |

## Why this score
- Posted in the last two weeks.
- 500 participants planned.

Source: ClinicalTrials.gov (U.S. National Library of Medicine) API v2 (https://clinicaltrials.gov/study/NCT07899463). Last refreshed: 2026-11-04T06:04:38.232Z.
From public ClinicalTrials.gov registrations. Sponsor and study level only: we never list investigators, contacts or participants. A registration describes a planned study and can change. Status changes are read from each study's current status, actual dates and latest posted update, not a full change history, so an update can be a correction rather than a new change. Verify on ClinicalTrials.gov.