Tissue-Free ctDNA Assay Predicts Distant Recurrence in Early Breast Cancer
Post-treatment detection of circulating tumor DNA 2 years after chemotherapy is strongly associated with distant recurrence and poorer overall survival.
Key takeaways
- A tissue-free epigenomic ctDNA assay detected tumor DNA in 5.8% of early breast cancer patients two years after chemotherapy.
- Among patients with detected ctDNA, 94% subsequently experienced a distant recurrence of their breast cancer.
- The ctDNA was identified at a median interval of 7.9 months before distant recurrence was clinically detected.
- ctDNA positivity was associated with a significantly shorter distant recurrence-free interval (hazard ratio of 33.3) and poorer overall survival (hazard ratio of 27.3).
A retrospective analysis of plasma samples from patients with early breast cancer indicates that tissue-free detection of circulating tumor DNA (ctDNA) can identify individuals at high risk of recurrence during follow-up. The study analyzed samples collected approximately two years after patients completed adjuvant chemotherapy, demonstrating that ctDNA detection was associated with a significantly shorter distant recurrence-free interval and poorer overall survival.
The research evaluated prospectively collected plasma samples from 313 patients with stage I-III early breast cancer who had no evidence of recurrence prior to sample collection. These patients participated in the SUCCESS-A phase III clinical trial. Using a tissue-free epigenomic ctDNA assay called Guardant Reveal, the analysis detected ctDNA in 5.8% of the samples.
Among patients who had ctDNA detected, 94% subsequently experienced a distant recurrence of their breast cancer. The assay detected the tumor DNA at a median interval of 7.9 months before the clinical recurrence was identified.
What Happened
Study Findings and Methods
Researchers prospectively collected plasma samples from patients with stage I-III early breast cancer enrolled in the SUCCESS-A phase III clinical trial (ClinicalTrials.gov identifier: NCT02181101). For this landmark analysis, they retrospectively analyzed samples from 313 patients who had no evidence of disease recurrence prior to sample collection, which occurred approximately two years after completing adjuvant chemotherapy.
The tissue-free epigenomic ctDNA assay detected ctDNA in 18 of the 313 patients (5.8%). Distant recurrence subsequently developed in 17 of these 18 patients (94%). The median interval between ctDNA detection and clinical recurrence was 7.9 months. For patients who had a plasma sample collected within one year before recurrence, the assay's sensitivity was 73% (11 out of 15). The specificity of the test was 99.6% (267 out of 268) in patients who did not experience recurrence.
What The Evidence Shows
Statistical Association with Outcomes
The landmark analysis, published in JCO Precision Oncology in September 2026, evaluated the association between post-treatment ctDNA detection and long-term patient outcomes. The statistical analysis showed that ctDNA positivity was strongly associated with a significantly shorter distant recurrence-free interval, reporting a hazard ratio of 33.3 (95% CI, 4.12 to 268; P < .0001). Additionally, ctDNA positivity was associated with poorer overall survival, carrying a hazard ratio of 27.3 (95% CI, 1.15 to 647; P < .0001).
What We Don't Know Yet
Study Limitations
The published study does not report the total sample size of the SUCCESS-A phase III clinical trial from which the 313 analyzed patients were drawn. Furthermore, because this was a retrospective analysis of prospectively collected samples, the study does not demonstrate whether initiating early interventions based on ctDNA detection improves long-term survival outcomes.
What Comes Next
Open Questions
The published source does not report planned next steps or future clinical trials by the researchers or study sponsors. Whether these findings will prompt prospective trials to evaluate the clinical outcomes of early therapeutic interventions in ctDNA-positive patients remains an open clinical question.
What This Means
Clinical Application
For patients with early-stage breast cancer, the tissue-free epigenomic ctDNA assay offers a highly specific prognostic tool during the post-treatment follow-up period. Detecting ctDNA approximately two years after adjuvant chemotherapy identifies a subgroup of patients at high risk for distant recurrence, allowing clinicians to stratify patients who may benefit from early interventions.
Original Source
PubMed (NCBI E-utilities): https://pubmed.ncbi.nlm.nih.gov/42696691/
Questions readers ask
- What did the study discover about ctDNA and breast cancer recurrence?
- The study found that detecting circulating tumor DNA (ctDNA) in plasma samples approximately two years after adjuvant chemotherapy was strongly associated with a significantly shorter distant recurrence-free interval. Of the patients with detected ctDNA, 94% subsequently experienced a distant recurrence, with the DNA detected at a median interval of 7.9 months before clinical recurrence.
- What is the accuracy of the tissue-free ctDNA assay used in this study?
- The Guardant Reveal assay demonstrated a specificity of 99.6% in patients who did not experience recurrence. For patients who had a plasma sample collected within one year before their recurrence, the assay had a sensitivity of 73%.
- Which patients were included in this landmark analysis?
- The retrospective analysis evaluated plasma samples from 313 patients with stage I-III early breast cancer who participated in the SUCCESS-A phase III clinical trial. All analyzed samples were collected approximately two years after patients finished adjuvant chemotherapy, and none of the patients had evidence of recurrence at the time of collection.
What this means
Clinical Application For patients with early-stage breast cancer, the tissue-free epigenomic ctDNA assay offers a highly specific prognostic tool during the post-treatment follow-up period. Detecting ctDNA approximately two years after adjuvant chemotherapy identifies a subgroup of patients at high risk for distant recurrence, allowing clinicians to stratify patients who may benefit from early interventions.
Limitations and uncertainties
- Study Limitations
- The published study does not report the total sample size of the SUCCESS-A phase III clinical trial from which the 313 analyzed patients were drawn. Furthermore, because this was a retrospective analysis of prospectively collected samples, the study does not demonstrate whether initiating early interventions based on ctDNA detection improves long-term survival outcomes.
