Implementation of ctDNA in Breast Cancer / ctDNA 08/21/2026

Ep. 1: ctDNA Testing in Different Breast Cancer Subtypes

Indian male oncologist in white lab coat, smiling for medical professional image, representing cancer research and treatment, on OncUpdates website. Matthew Kurian, MD Professional portrait of a smiling man in a dark suit and striped tie, suitable for medical or healthcare-related content on OncUpdates. Wassim McHayleh, MD 1. Smiling female healthcare professional in white coat, headshot portrait, oncology specialist in medical setting for cancer treatment and research. Eleonora Teplinsky, MD Smiling man with beard wearing a white shirt, professional headshot, suitable for oncology or cancer research content, emphasizing healthcare and medical expertise. Rahul Gosain, MD, MBA Oncologist smiling in white coat, highlighting cancer research and treatment expertise, with a bow tie, in a bright medical setting. Rohit Gosain, MD

Key Points

  • Circulating tumor DNA (ctDNA) testing is evolving across different cancer types, and guidelines are changing rapidly.
  • Triple-negative breast cancer (TNBC) and HER2–positive breast cancer exhibit more DNA shedding, while hormone receptor (HR)–positive breast cancer exhibits very low shedding.

ctDNA Testing Guidelines and Unique Considerations for Breast Cancer

During a panel discussion about ctDNA testing in breast cancer, Eleonora Teplinsky, MD, of Valley-Mount Sinai Comprehensive Cancer Care, and Matthew Kurian, MD, of St. Elizabeth Healthcare, reviewed the most recent American Society of Clinical Oncology (ASCO) guideline update for ctDNA testing in solid tumors and lymphoma and specific considerations for ctDNA in breast cancer.

Broadly, the ASCO guideline suggests that, outside of a clinical trial, ctDNA testing should only be offered to patients if the results of testing can guide clinical decision making or determine eligibility for participation in a clinical trial. The guideline acknowledges that ctDNA trials are ongoing and the field is rapidly evolving, but for today, it does not recommend using ctDNA testing other than for identifying genetic alterations. As the evidence matures, disease-specific and subtype-specific recommendations may change.

While trials and guidelines are still investigating how ctDNA can guide treatment, studies have already characterized some distinct ctDNA profiles across breast cancer subtypes. Notably, TNBC and HER2–positive breast cancer are associated with more ctDNA shedding, while HR–positive breast cancer exhibits very low shedding, according to Dr. Kurian. In addition, while ctDNA is prognostic for recurrence, time to recurrence can be substantially longer for HR–positive breast cancer compared with TNBC. As time goes on, oncologists will need to determine which populations and treatment settings are most likely to benefit from ctDNA testing.