Circulating Tumor DNA in Blood After Pre-Surgery Treatment Signals Breast Cancer Recurrence Risk

Fragments of circulating tumor DNA (ctDNA) in the bloodstream have emerged as a transformative biomarker in breast cancer management, with recent research underscoring their critical role in predicting disease relapse. Presented at the 15th European Breast Cancer Conference (EBCC15) in Barcelona, a comprehensive study led by Dr. Elisa Agostinetto and her colleagues highlights the prognostic power of ctDNA following neoadjuvant therapy — anti-cancer treatments administered before surgery — marking a significant advance in personalized oncology care.

This groundbreaking investigation involved 81 early breast cancer patients enrolled across two leading cancer institutes: the Institut Jules Bordet in Brussels and the Instituto Nazionale dei Tumori in Milan. These patients, ranging in age from 27 to 75, predominantly had tumors less than 5 centimeters in diameter, commonly accompanied by lymph node involvement. Notably, 60% of participants bore the triple-negative breast cancer subtype, known for its aggressive nature and relative resistance to conventional therapies.

The analytical approach in this multicenter European study involved serial blood sampling at three critical junctures: at diagnosis (baseline), immediately after the completion of neoadjuvant therapy but before surgery, and throughout an extended follow-up period averaging seven years. By quantifying ctDNA sequences in plasma samples, the research team sought to understand how tumor DNA circulating post-treatment correlates with the risk of cancer recurrence, metastasis, or mortality.

Findings revealed that while ctDNA was detected in 57% of patients at baseline, this prevalence sharply declined to 17% following neoadjuvant therapy. Importantly, the presence of ctDNA at this post-treatment stage emerged as a robust predictor of relapse: patients harboring detectable ctDNA were found to be 3.5 times more likely to experience breast cancer recurrence, independent of traditional prognostic factors such as tumor size, patient age, and hormone receptor status. These results persist even in patients achieving pathological complete response (pCR) — where no residual tumor is detectable by conventional pathology — underscoring the sensitivity of ctDNA as a marker of minimal residual disease.

This study’s longitudinal design and substantial cohort size represent marked improvements over prior investigations, which often suffered from limited patient numbers and short follow-up durations. By capturing real-world clinical data over years, Dr. Agostinetto’s team demonstrated that ctDNA serves not only as a reflection of tumor burden but also as a harbinger of molecular relapse months before conventional imaging or clinical symptoms emerge.

Intriguingly, the analysis uncovered a strong association between ctDNA positivity and hormone receptor-negative (HR-) breast cancers, which are typically more aggressive and less responsive to hormone-based therapies. Approximately 64% of the study population had HR- disease at baseline, aligning with the high frequency of triple-negative cases. This molecular subtype association suggests ctDNA could play a pivotal role in stratifying patients who might benefit from intensified or alternative post-surgical treatments.

The implications of employing ctDNA as a post-neoadjuvant biomarker for breast cancer are profound. It offers oncologists a powerful tool to tailor adjuvant treatment regimens, potentially escalating therapy in patients at high relapse risk while sparing lower-risk individuals from overtreatment and its attendant toxicities. The study advocates for integrating ctDNA monitoring into clinical pathways, especially given its minimally invasive nature compared to biopsies, enabling dynamic and longitudinal disease surveillance.

Despite these promising results, Dr. Agostinetto cautions that ctDNA testing after neoadjuvant therapy is not yet part of standard clinical practice outside of research settings. She emphasizes the necessity for prospective, randomized clinical trials where treatment decisions are guided by ctDNA status to validate whether early intervention based on ctDNA positivity translates into improved patient outcomes. Such trials would clarify the clinical utility and cost-effectiveness of routine ctDNA surveillance in breast cancer management.

The research collaboration highlights the value of combining expertise across European cancer centers and the importance of sustained follow-up to capture late recurrences that might otherwise go undetected. The study’s robust design, encompassing extensive patient data across two centers and nearly a decade of monitoring, establishes a new benchmark in biomarker research.

Experts outside the study have recognized its significance. Dr. Javier Cortés, co-director of the International Breast Cancer Center, remarked that this work strengthens the mounting evidence for ctDNA’s prognostic relevance across breast cancer subtypes. He underscored the urgent need for clinical trials investigating whether ctDNA-driven treatment adaptations can reliably improve survival and quality of life.

As breast cancer therapies evolve toward precision medicine, the integration of sensitive molecular biomarkers like ctDNA stands poised to revolutionize patient stratification and management. This study’s insights into ctDNA’s predictive power following neoadjuvant therapy illuminate a promising path forward for detecting minimal residual disease and preventing relapse through timely, personalized therapeutic interventions.

In summary, this pioneering research confirms that circulating tumor DNA post-neoadjuvant therapy is not merely a passive molecular footprint but a dynamic and actionable biomarker. Its detection heralds a higher risk of disease recurrence, enabling oncologists to identify patients who most require aggressive follow-up or additional treatments, thereby optimizing clinical outcomes and heralding a new era in breast cancer care.

News Publication Date: March 27, 2024

References: Abstract no: 12, 15th European Breast Cancer Conference (EBCC15)