ASCO 2025 Breast Cancer Guidelines
Most Recent Update: Sentinel Lymph Node Biopsy (2025)
The most recent ASCO guideline from 2025 addresses sentinel lymph node biopsy (SLNB) in early-stage breast cancer, providing updated recommendations on axillary staging procedures. 1
Comprehensive ASCO Breast Cancer Management Guidelines
Hormone Receptor-Positive, HER2-Negative Metastatic Disease (Updated 2021)
First-Line Therapy
Postmenopausal women should receive a nonsteroidal aromatase inhibitor (AI) combined with a CDK4/6 inhibitor as first-line treatment. 1
- Premenopausal women require ovarian suppression or ablation combined with AI and CDK4/6 inhibitor 1
- Male patients should receive AI with CDK4/6 inhibitor plus gonadotropin-releasing hormone analog 1
- Endocrine therapy is preferred over chemotherapy except for immediately life-threatening disease or rapid visceral progression during adjuvant endocrine therapy 1
Second-Line Therapy
Fulvestrant 500 mg with CDK4/6 inhibitor should be offered to patients progressing on AI therapy or recurring within 1 year of adjuvant AI. 1
- Sequential hormone therapy continues until unequivocal disease progression documented by imaging, clinical examination, or disease-related symptoms 1
- A specific hormonal agent may be reused if recurrence occurs ≥12 months after last treatment 1
Targeted Therapy Based on Biomarkers
Patients with PIK3CA-mutated disease should receive alpelisib combined with fulvestrant after progression on AI. 1
Patients with germline BRCA1/2 mutations should receive oral PARP inhibitor (olaparib or talazoparib) in first-through-third-line settings rather than chemotherapy. 1
- PARP inhibitors demonstrate high response rates in germline PALB2 mutation carriers and somatic BRCA mutations, though evidence is from smaller single-arm studies 1
HER2-Positive Advanced Breast Cancer (Updated 2018)
First-Line Treatment
Trastuzumab, pertuzumab, and taxane combination is the standard first-line therapy for HER2-positive metastatic breast cancer. 1
- This recommendation applies unless contraindication to taxanes exists 1
- Chemotherapy should continue for minimum 4-6 months or until maximum response, depending on toxicity and absence of progression 1
- HER2-targeted therapy continues until progression or unacceptable toxicities 1
Second-Line Treatment
Trastuzumab emtansine (T-DM1) is recommended for second-line therapy after progression on first-line HER2-targeted treatment. 1
Third-Line and Beyond
Other HER2-targeted therapy combinations or T-DM1 (if not previously administered) should be offered, with consideration of pertuzumab if not previously received. 1
Hormone Receptor-Positive/HER2-Positive Disease
- Selected patients may receive endocrine therapy plus HER2-targeted therapy or endocrine therapy alone instead of standard first-line chemotherapy-based regimens 1
- This applies specifically to patients with hormone receptor-positive and HER2-positive disease 1
HER2-Negative Metastatic Disease (Endocrine-Pretreated or Hormone Receptor-Negative) (Updated 2021)
Chemotherapy Approach
Sequential single-agent chemotherapy is preferred over combination therapy, though combination regimens may be considered for symptomatic or immediately life-threatening disease. 1
- The main benefit is less toxicity and better quality of life with single-agent therapy 1
- Combination therapy is reserved for rapid progression with organ dysfunction 1
PARP Inhibitors for BRCA Mutations
Oral PARP inhibitor should be offered in first-through-third-line settings for patients with germline BRCA1/2 mutations rather than chemotherapy. 1
Combined Endocrine and Chemotherapy
Combined endocrine therapy and chemotherapy is not recommended. 1
Male Breast Cancer (2020)
Adjuvant Endocrine Therapy
Tamoxifen for 5 years is the standard adjuvant therapy for hormone receptor-positive male breast cancer. 1, 2
- Men with high recurrence risk after completing 5 years of tamoxifen may receive additional 5 years of tamoxifen 1, 2
- Aromatase inhibitors alone are less effective in men and require combination with gonadotropin-releasing hormone agonist/antagonist if tamoxifen is contraindicated 1, 2
Advanced/Metastatic Disease
Men with hormone receptor-positive, HER2-negative metastatic disease should receive endocrine therapy as first-line treatment except for visceral crisis or rapidly progressive disease. 1, 2
- Options include tamoxifen, AI with GnRH agent, or fulvestrant 1, 2
- CDK4/6 inhibitors are used in men with same indications as women 1, 2
Critical Contraindication
Testosterone/androgen supplementation must not be used in men with breast cancer. 1, 2
Genetic Testing
All men with breast cancer should be offered genetic counseling and germline genetic testing. 1, 2
- BRCA2 mutations occur in 4-16% of male breast cancer cases 3
- Other mutations (CHEK2, PALB2, PTEN) account for approximately 20% collectively 3
Surveillance
Ipsilateral annual mammogram should be performed for men treated with lumpectomy. 1, 2
- Contralateral annual mammogram may be offered to men with genetic predisposing mutations 1, 2
- Breast MRI is not routinely recommended 1, 2
Sentinel Lymph Node Biopsy (2025)
The 2025 ASCO guideline update addresses optimal use of SLNB in early-stage breast cancer, including considerations for omitting SLNB in select patients based on negative axillary ultrasound and specific tumor characteristics. 1
- Cost-effectiveness analysis demonstrates that SLNB omission in postmenopausal women with cT1-T2 N0, hormone receptor-positive, HER2-negative breast cancer is associated with lower costs and higher quality of life 1
Key Principles Across All Guidelines
Treatment should continue until unequivocal evidence of disease progression as documented by imaging, clinical examination, or disease-related symptoms. 1
Patients should be encouraged to enroll in clinical trials, including those receiving first-line treatment. 1
Hormone therapy should be offered to patients whose tumors express any level of estrogen and/or progesterone receptors. 1