The 19th St. Gallen international breast cancer conference ‘primary therapy of patients with early breast cancer. Evidence, controversies, consensus’: key moments and breakthroughs

• Conference Overview
  Held March 12–15, 2025 in Vienna with >3,100 global participants.
  Focused on early breast cancer (BC): evidence, controversies, consensus, and breakthroughs.
  Included lectures, debates, poster sessions, and the renowned St. Gallen Consensus Session.
  Hansjoerg Senn Memorial Lecture was introduced to honor a major contributor to BC care. 
  
  🔬 Systemic Therapy & Novel Agents
  Goal of early BC therapy is to improve overall survival (OS) through better systemic and local treatment.
  Surrogate endpoints (e.g., pathological complete response) are crucial for accelerating drug development.
  New endocrine therapies (SERDs) are being evaluated, with emphasis on QoL and resistance mechanisms.
  Anti-HER2 advances from metastatic setting are being translated to early BC, including adaptive trial designs.
  Antibody-drug conjugates (ADCs) hold potential in early BC; ongoing trials are evaluating various indications. 
  
  🧬 Liquid Biopsy & Biomarkers
  ctDNA and liquid biopsy show promise for minimal residual disease (MRD) detection and relapse risk stratification.
  Tumor-informed assays have higher sensitivity than tumor-agnostic panels.
  Circulating tumor cells (CTCs) are prognostic but less sensitive; CHIP mutations may confound results.
  Multiple trials are exploring ctDNA as a tool for guiding post-treatment strategies. 
  
  HER2+ Breast Cancer
  Trastuzumab remains a foundational therapy after 20 years.
  Duration of trastuzumab (6 vs. 12 months) continues to be debated; 12 months remains standard.
  Improved HER2 testing and classification helps tailor therapies, especially in HER2-low disease.
  De-escalation strategies (e.g., PET-adapted) are under study for selected patients.
  Residual disease post-neoadjuvant therapy moves toward T-DM1 or other combinations; new trials are ongoing. 
  
  Tailoring Treatment & De-Escalation
  Omitting radiotherapy (RT) or endocrine therapy (ET) in very low-risk patients is under investigation.
  Minimally invasive alternatives (e.g., cryoablation) are being evaluated to reduce surgical burden.
  Older patients need individualized decision making rather than age-based exclusion from therapy.
  Tools like ESMO Magnitude of Clinical Benefit Scale can help weigh benefits vs toxicity. 
  
  Surgery & Local Management
  Breast-conserving surgery (BCS) remains preferred when feasible; mastectomy does not guarantee survival benefit.
  Radiotherapy tailoring (partial, hypofractionation) reduces toxicity while maintaining control.
  Post-neoadjuvant surgery focuses on resection of residual disease; MRI radiomics and biopsies aid prediction.
  Reconstruction decisions must be individualized, involving patient preferences and RT considerations. 
  
  ER+ Disease Nuances
  Optimizing adjuvant therapy (ET, CDK4/6 inhibitors, genomic assays) depends on recurrence risk and biomarkers.
  Chemotherapy benefit varies by genomic risk scores and age—particularly in premenopausal women.
  Extended ET decisions benefit from clinical, genomic, and novel biomarkers like ctDNA.
  Invasive lobular carcinoma (ILC) and ER-low tumors need refined imaging and therapeutic stratification. 
  
  Artificial Intelligence (AI) Integration
  AI has potential to enhance:
  Biomarker discovery and response prediction
  Treatment planning and radiation delivery
  Target identification and clinical decision support
  Collaboration between AI developers and clinicians is essential for clinical implementation. 
  
  Imaging & Staging Updates
  PET-CT may be useful in higher-stage early BC; routine use in stage I remains limited.
  Breast MRI improves staging but increases interventions without clear outcome benefit; selective use recommended.
  Follow-up imaging remains guided by existing evidence; future strategies might integrate new technologies and ctDNA. 
  
  Hereditary BC & Prevention
  Germline mutations (BRCA1/2, PALB2, ATM, CHEK2) justify altered management and intensive screening.
  Risk-reducing surgeries lower incidence, though survival benefits require longer follow-up.
  Non-surgical options (e.g., intensified screening, risk-reducing medications) are important for many carriers. 
  
  Axillary Management
  Sentinel lymph node biopsy (SLNB) remains standard for clinically node-negative patients.
  Omission of upfront axillary surgery is considered in select scenarios with multidisciplinary input.
  Trials are evaluating safe approaches to avoid full axillary dissection post-neoadjuvant therapy. 
  
  Clinical Trials & Patient-Centered Design
  High-quality trials require real-world applicability, patient involvement, meaningful endpoints, and QoL measures.
  Trial design frameworks (e.g., SPIRIT, PRECIS-2) help balance explanatory vs pragmatic objectives. 
  
  Special Populations
  BC during pregnancy requires tailored imaging and therapy planning to optimize maternal and fetal safety.
  Young patients and those with reproductive concerns need individualized counseling and treatment adaptation. 

https://ecancer.org/en/journal/article/2075-the-19th-st-gallen-international-breast-cancer-conference-primary-therapy-of-patients-with-early-breast-cancer-evidence-controversies-consensus-key-moments-and-breakthroughs?utm_campaign=automated-emails&utm_source=siteupdates-en-html-20260213&utm_medium=email&utm_target=d8628274966ebe70f6f44ff9393f2797c2d952c553cc7fa3f43de5e1c17fd7171edb509c851169c954d77de3b71e4aa86c3e034376f2253f-f23386