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.

Subject of Research: People

Article Title: Circulating tumor DNA at completion of neoadjuvant therapy is an independent prognostic marker: an individual patient-level pooled analysis of two prospective studies

News Publication Date: March 27, 2024

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

Image Credits: Dr. Elisa Agostinetto

Axillary lymph node dissection has long been the conventional approach for managing metastasis in regional lymph nodes, often involving the removal of numerous lymph nodes in the armpit to eliminate residual cancer and reduce recurrence risk. However, ALND is frequently associated with significant postoperative complications, most notably lymphoedema—a chronic and frequently debilitating swelling of the arm caused by lymphatic fluid accumulation due to disrupted lymphatic drainage. The prospect of radiotherapy as a substitute aims to mitigate these morbidity risks while maintaining oncological efficacy.

The ADARNAT trial concentrated on patients who had undergone neoadjuvant systemic therapies, such as chemotherapy or hormone therapy, prior to surgery. These treatments often reduce tumor size and eradicate metastasis in lymph nodes, leaving only a limited number of sentinel lymph nodes positive for cancer at the time of surgery. This specific subset—patients with one or two involved sentinel nodes post-neoadjuvant therapy—might not derive significant added benefit from extensive surgical removal of axillary nodes, which potentially subjects patients to unnecessary side effects.

Between mid-2021 and early 2023, the trial enrolled 272 patients diagnosed with breast cancer exhibiting metastasis in only one or two sentinel lymph nodes following systemic therapy. Participants were randomized to receive either axillary radiotherapy or conventional surgical dissection, with both groups receiving radiation to the breast and chest regions. The median follow-up period was two years, a critical window for assessing short-term oncologic safety and adverse effects.

Intriguingly, no axillary cancer recurrences were detected among patients treated with ART, whereas a single recurrence (about 1.8%) was identified in the ALND group. Rates of distant metastasis were comparable between the two cohorts—4.4% in the ART arm and 5.5% with ALND—further suggesting equivalency in systemic disease control. Mortality within this follow-up was low and slightly favored the ART group. Importantly, lymphoedema incidence, while not statistically significant, trended lower in patients receiving radiotherapy (18.9% versus 26.7% in the surgical arm), implying a clinical benefit in terms of reducing this common complication.

Beyond cancer control, the nature and severity of treatment-related toxicities form a crucial consideration. The study observed a higher frequency of acute skin reactions in the ART group, with 27.8% experiencing grade 2 or worse dermatitis compared to 13.3% following ALND. Manifestations included erythema, pigmentation changes, and peeling. However, these reactions were transient and manageable, and no significant long-term dermatologic differences were noted between groups.

Functional outcomes, specifically arm mobility, were also evaluated. Mild, transient impairments in arm elevation and lateral movement occurred slightly more often in ART patients but did not affect daily activities significantly. Measures of quality of life aligned closely between the arms, with a subtle trend favoring those receiving radiotherapy. These data collectively support the contention that axillary radiotherapy offers a feasible, less morbid alternative with qualitatively similar patient experience post-treatment.

Principal investigator Professor Amparo Garcia-Tejedor underscored the preliminary nature of these results, cautioning against hastily changing clinical practice prior to the completion of the full phase III trial. Yet, she indicated that these findings lay the foundational rationale for de-escalating axillary surgery in favor of radiotherapy, especially in patients demonstrating good response to neoadjuvant therapy.

Dr. Maria Laplana-Torres, radiation oncologist and trial co-presenter, emphasized the importance of this ongoing research in refining personalization of breast cancer care. The ability to tailor axillary treatment intensity based on individual disease burden promises to minimize adverse effects without compromising cancer outcomes. Such advances align with the broader movement toward more precise, patient-centered oncology protocols.

Looking ahead, the main phase III segment has already enrolled over 500 patients and aims for robust statistical power to definitively assess long-term survival, recurrence, and quality of life metrics over a planned five-year follow-up. If the final data mirror current trends, it could herald a substantive paradigm shift—encouraging clinicians to favor radiotherapy over surgery in selected populations, thereby sparing many women from the lifelong burden of lymphoedema and other surgical complications.

The chair of the conference, Professor Isabel Rubio, echoed the cautious optimism permeating the breast oncology community. She highlighted that while the pilot data encourage pursuit of less invasive alternatives, further stratification of patients to identify those who might safely omit both surgery and radiation is a promising frontier. Ultimately, such innovation could revolutionize axillary management, balancing oncologic safety with enhanced patient quality of life.

This evolving evidence base underscores the critical imperative of well-designed randomized controlled trials to delineate optimal treatment strategies in an era increasingly defined by precision medicine. The ADARNAT trial represents a significant step forward in understanding how to safely reduce the morbidity burden associated with breast cancer treatment without compromising the ultimate goal—eliminating cancer and prolonging survival.

Subject of Research: People

Image Credits: ADARNAT team

Keywords: Breast cancer, Breast carcinoma, Surgery, Cancer treatments, Radiation therapy, Surgical procedures, Personalized medicine, Side effects, Physical rehabilitation