19th St. Gallen International Breast Cancer Conference (2025)

19th St. Gallen International Breast Cancer Conference (2025)

Consensus Recommendations – Early Breast Cancer

🧬 1️⃣ ER-Positive / HER2-Negative Disease

🔹 Genomic Testing

Strong support for multigene assays (Oncotype DX, MammaPrint, etc.) in:

Node-negative disease, 1 to 3 positive nodes (especially postmenopausal)

In premenopausal patients with 1 to 3 nodes → chemotherapy often still favored even with low genomic risk.

🔹 Chemotherapy

Postmenopausal:

N1 (1 to 3 nodes), low genomic risk → chemo can be omitted.

Premenopausal:

N1 disease → chemotherapy generally recommended (ovarian suppression contribution acknowledged but not universally accepted as replacement).

🔹 Ovarian Function Suppression (OFS)

Recommended in:

High-risk premenopausal patients Node-positive disease AI + OFS preferred over tamoxifen alone in higher-risk settings.

🔹 CDK4/6 Inhibitors

Abemaciclib recommended in: High-risk node-positive (monarchE-like criteria) Ribociclib data discussed but not yet fully standard globally.

🟡 2️⃣ HER2-Positive Early Breast Cancer

🔹 Neoadjuvant Therapy

Standard for:

Tumors ≥2 cm, Node-positive disease

Preferred regimen: Taxane + dual anti-HER2 (trastuzumab + pertuzumab)

🔹 Residual Disease After Neoadjuvant Therapy

T-DM1 (KATHERINE data) remains standard.

🔹 Duration of Trastuzumab

12 months remains consensus standard.

6 months acceptable only in select lower-risk or toxicity cases.

🔹 De-escalation

Small node-negative HER2+ (<2 cm): TH regimen acceptable (APT-like approach). Ongoing interest in response-adapted therapy.

🔵 3️⃣ Triple-Negative Breast Cancer (TNBC)

🔹 Neoadjuvant Therapy

Standard:

Anthracycline + taxane backbone Addition of pembrolizumab supported in stage II to III

🔹 Residual Disease

Continue pembrolizumab (KEYNOTE-522 strategy) Capecitabine considered if no prior immunotherapy

🔹 BRCA-Mutated

Adjuvant olaparib recommended (OlympiA criteria)

🟢 4️⃣ Axillary Management

🔹 Clinically Node-Negative

Sentinel lymph node biopsy (SLNB) standard.

🔹 1 to 2 Positive Sentinel Nodes (Upfront Surgery)

Omission of ALND supported if: Undergoing breast-conserving therapy Whole-breast RT planned (Z0011 principles upheld)

🔹 After Neoadjuvant Therapy

If cN+ → ycN0: SLNB acceptable if ≥ 3 nodes retrieved + dual tracer. Residual nodal disease → ALND still recommended in most settings.

🔴 5️⃣ Radiation Therapy

🔹 Hypofractionation

Standard for most patients.

Ultra-hypofractionation (FAST-Forward-like) widely accepted.

🔹 Omission of RT

May be considered in:

Age ≥ 70 Small ER+ tumors Planned endocrine therapy

🔹 Regional Nodal Irradiation

Recommended in:

Node-positive disease High-risk biology

🟠 6️⃣ De-escalation Themes

Avoid overtreatment in:

Low-risk luminal A disease Elderly / frail patients Tailor treatment based on: Biology > anatomy alone Genomic profiling Patient preference

🧪 7️⃣ Liquid Biopsy & MRD

ctDNA promising but:

Not yet standard for treatment decision

Still investigational for escalation / de-escalation

🧬 8️⃣ Germline Mutation Carriers

BRCA1/2:

Consider bilateral mastectomy (case-dependent)

Adjuvant olaparib in high-risk early disease

PALB2 increasingly treated similarly to BRCA in high-risk scenarios.

🧠 9️⃣ Artificial Intelligence & Imaging

MRI not routine for all early-stage patients.

PET-CT not recommended for stage I routine staging.

AI emerging for:

Risk stratification

Imaging interpretation

Treatment personalization

🎯 Key Global Themes of St. Gallen 2025

Precision > escalation Biology-driven treatment

Safe de-escalation when supported by data

Increased use of CDK4/6 inhibitors and immunotherapy in early disease

Continued minimization of axillary surgery