This Clinical Trial is a Retrospective, Multicenter Cohort Study Evaluating the Real-world Characteristics and Risk of Disease Recurrence in Hormone Receptor-positive, HER2-negative Early Breast Cancer. (PRIORITY)

Real-world Characteristics and Risk of Disease Recurrence in Hormone Receptor-positive, HER2-negative Early Breast Cancer: a Multi-center Retrospective Cohort Study in Korea

• Primary objective: To describe event-free survival (EFS) in patients with stage I-III HR+/HER2- early breast cancer (EBC) who received curative surgery followed by systemic therapy.
• Secondary objectives: Include assessment of relapse-free survival (RFS), distant disease-free survival (DDFS), distant relapse-free survival (DRFS), overall survival (OS), site of distant recurrence, and time-to-next treatment (TTNT), as well as evaluating the association between clinicopathologic/treatment variables and clinical outcomes.
• Key inclusion criteria: Adults (≥18 years) with stage I-III HR+/HER2- invasive breast cancer who underwent curative surgery
• Key exclusion criteria: HR- or HER2+ tumors, de novo stage IV, or lack of curative-intent surgery

Study Overview

• Status: Not yet recruiting
• Conditions: Early Breast Cancer

• Study Type: Observational
• Enrollment (Estimated): 100000

Contacts and Locations

• Study Contact: Name: Yeon Hee PARK, Ph.D; Phone Number: 82-2-3410-1780; Email: yeonh.park@samsung.com

Study Locations

• South Korea
  • Seoul, South Korea, 06351
    • Samsung Medical Center
    • Contact: SeonA Jang, CRC; Phone Number: 82-2-3410-1254; Email: seona.jang@samsung.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

Key inclusion criteria: Adults (≥18 years) with stage I-III HR+/HER2- invasive breast cancer who underwent curative surgery Key exclusion criteria: HR- or HER2+ tumors, de novo stage IV, or lack of curative-intent surgery

Description

Inclusion Criteria:

1. Patients (female or male) with a histologically confirmed first diagnosis of invasive breast cancer, identified by International Classification of Diseases, 10th Revision (ICD-10) code C50.x, between January 1, 2010, and December 31, 2023.* The date of diagnosis will be based on the initial pathology report or the date reported to the Korea Central Cancer Registry (KCCR).
2. Age 18 years or older at the time of initial diagnosis.
3. Anatomical stage I, II, or III disease at initial diagnosis, staged according to the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, using the edition contemporary to the time of diagnosis.
4. Confirmed HR-positive disease, defined as estrogen receptor (ER) and/or progesterone receptor (PR) expression in ≥1% of invasive tumor cells on immunohistochemistry (IHC), or an Allred proportion score of 2 or higher.
5. Confirmed HER2-negative disease, defined as an IHC score of 0 or 1+, or an IHC score of 2+ with a negative in situ hybridization (ISH) result (e.g., fluorescence in situ hybridization or silver in situ hybridization). Patients recorded as HER2-negative without a specific score available will also be included.
6. Documented history of having received definitive (curative-intent) surgery for the primary breast cancer (e.g., breast-conserving surgery or mastectomy).

Exclusion Criteria:

1. Patients (female or male) with a histologically confirmed first diagnosis of invasive breast cancer, identified by International Classification of Diseases, 10th Revision (ICD-10) code C50.x, between January 1, 2010, and December 31, 2023.* The date of diagnosis will be based on the initial pathology report or the date reported to the Korea Central Cancer Registry (KCCR).
2. Age 18 years or older at the time of initial diagnosis.
3. Anatomical stage I, II, or III disease at initial diagnosis, staged according to the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, using the edition contemporary to the time of diagnosis.
4. Confirmed HR-positive disease, defined as estrogen receptor (ER) and/or progesterone receptor (PR) expression in ≥1% of invasive tumor cells on immunohistochemistry (IHC), or an Allred proportion score of 2 or higher.
5. Confirmed HER2-negative disease, defined as an IHC score of 0 or 1+, or an IHC score of 2+ with a negative in situ hybridization (ISH) result (e.g., fluorescence in situ hybridization or silver in situ hybridization). Patients recorded as HER2-negative without a specific score available will also be included.
6. Documented history of having received definitive (curative-intent) surgery for the primary breast cancer (e.g., breast-conserving surgery or mastectomy).

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
EFS (Event Free Survival)	The time from the index date (date of initiation of first systemic therapy or date of curative surgery, whichever occurs first) to the date of the first occurrence of any of the following events: disease progression that precludes the ability to perform definitive surgery (for patients receiving neoadjuvant therapy), invasive local or distant recurrence, the occurrence of a second primary invasive cancer, or death from any cause.	Its temporal window, which spans from 2010 to 2023

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
RFS	Time from index date to any recurrence (local/regional/distant) or death from any cause	Its temporal window, which spans from 2010 to 2023
DDFS	Time from index date to distant recurrence, second non-breast primary cancer, or death from any cause	Its temporal window, which spans from 2010 to 2023.
DRFS	Time from index date to distant recurrence or death from any cause	Its temporal window, which spans from 2010 to 2023
OS	Time from index date to death from any cause	Its temporal window, which spans from 2010 to 2023
Site of initial distant recurrence	The anatomical location(s) of the first documented distant metastatic lesion(s)	Its temporal window, which spans from 2010 to 2023
TTNT	Time from the initiation of first-line systemic therapy for advanced/metastatic disease to the initiation of a subsequent line of therapy or death from any cause	Its temporal window, which spans from 2010 to 2023

Collaborators and Investigators

• Sponsor: Samsung Medical Center
• Collaborators: Novartis

Study record dates

Study Major Dates

• Study Start (Estimated): December 17, 2025
• Primary Completion (Estimated): January 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: December 16, 2025
• First Submitted That Met QC Criteria: December 16, 2025
• First Posted (Actual): December 30, 2025

Study Record Updates

• Last Update Posted (Actual): December 30, 2025
• Last Update Submitted That Met QC Criteria: December 16, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Early breast cancer retrospective cohort study
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms
• Other Study ID Numbers: 2025-08-005

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: It will be decided later.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No