ESMO Breast Cancer 2026 Highlights: TRAK-ER

Harold Burstein, MD, PhD, and Erica Mayer, MD, MPH discuss results from the TRAK-ER trial, which were presented at the 2026 ESMO Breast Cancer Congress.

June 26, 2026

Dana-Farber

Overview

The TRAK-ER trial evaluated the use of ctDNA surveillance in high-risk HR-positive/HER2-negative early breast cancer patients receiving adjuvant endocrine therapy. Key findings included a 1.87% ctDNA detection rate and a significant proportion of patients exhibiting clinical recurrence at the time of initial ctDNA detection, as reported in the trial results.

Background

The TRAK-ER trial is significant as it explores the role of circulating tumor DNA (ctDNA) in monitoring high-risk breast cancer patients during adjuvant therapy.

Data Highlights

Parameter	Value
ctDNA Detection Rate	1.87%
Patients with ctDNA Detected	11.6%
Initial ctDNA Detection with Recurrence	42.9%
Assay Design Failure Rate	16.1%

Key Findings

ctDNA was detected in 1.87% of samples from the TRAK-ER trial.
11.6% of patients had at least one ctDNA-positive result during surveillance.
42.9% of patients with initial ctDNA detection had clinically or radiographically recurrent disease.
Assay design failed in 16.1% of cases, indicating technical challenges.

Clinical Implications

Current guidelines suggest that while ctDNA positivity correlates with recurrence risk, routine surveillance based solely on ctDNA results remains unproven.