From the Guidelines
The St. Gallen criteria for determining risk in hormone receptor (HR) positive breast cancer are based on factors such as tumor size, grade, and hormone receptor status, with low-risk patients having tumors ≤ 2 cm, grade 1, and positive estrogen and/or progesterone receptors, while high-risk patients have factors like tumors greater than 2 cm, grade 2 to 3, or age younger than 35 years 1.
Key Factors
- Tumor size: ≤ 2 cm for low risk, greater than 2 cm for high risk
- Grade: 1 for low risk, 2 to 3 for high risk
- Hormone receptor status: positive estrogen and/or progesterone receptors for low risk, negative for high risk
- Age: ≥ 35 years for low risk, younger than 35 years for high risk
Clinical Application
These criteria are used to determine the need for systemic adjuvant therapy in node-negative breast cancer patients, with low-risk patients potentially not requiring adjuvant chemotherapy and high-risk patients likely benefiting from it 1.
Evidence Basis
The validation of the 2001 St Gallen risk categories using a database from the Spanish Breast Cancer Research Group (GEICAM) supports the use of these criteria in clinical practice, showing that patients classified as low risk had a favorable outcome, while those classified as high risk had a higher risk of recurrence 1.
From the Research
St. Gallen Criteria for Determining Risk in HR-Positive Breast Cancer
The St. Gallen criteria are used to determine the risk of recurrence in hormone receptor (HR)-positive breast cancer. The criteria include:
- Tumor size and grade
- Lymph node status
- Ki-67 index, which is a measure of tumor proliferation
- Hormone receptor status, including estrogen receptor (ER) and progesterone receptor (PR) status
- HER2 status
Ki-67 Index and St. Gallen Criteria
The Ki-67 index is a key component of the St. Gallen criteria, with high Ki-67 levels indicating a higher risk of recurrence 2, 3, 4, 5. The optimal cut-off value for Ki-67 is still debated, but a value of ≥20% is often used to define high Ki-67 expression 2, 3.
- High Ki-67 expression (≥20%) is associated with a worse prognosis and may predict benefit from adjuvant chemotherapy 2, 4.
- Ki-67 evaluation at the hottest spot, rather than the average score across the section, is a stronger predictor of clinical outcome in patients with HR-positive/HER2-negative breast cancer treated with adjuvant tamoxifen monotherapy 5.
Clinical Application of St. Gallen Criteria
The St. Gallen criteria are used to guide treatment decisions for patients with HR-positive breast cancer.
- Patients with high-risk disease, as defined by the St. Gallen criteria, may benefit from adjuvant chemotherapy in addition to endocrine therapy 6, 2.
- Patients with low-risk disease may be treated with endocrine therapy alone 6, 4.
- The use of Ki-67 testing and treatment patterns in patients with HR-positive breast cancer varies in clinical practice, with high-grade tumors and lymph node involvement predicting high Ki-67 expression and guiding treatment decisions 3.