Expanding Criteria for Prognostic Stage IA in Hormone Receptor-Positive Breast Cancer

Area of Science:

• Oncology
• Cancer Research
• Clinical Staging

Background:

• The prognostic value of low recurrence score (RS) results within the American Joint Committee on Cancer (AJCC) eighth edition staging is understudied.
• Investigating expanded RS criteria for potential downstaging in AJCC pathologic prognostic staging is crucial.

Purpose of the Study:

• To evaluate the prognostic significance of low recurrence score (RS) results in AJCC eighth edition pathologic prognostic staging.
• To determine if expanded RS criteria can be utilized for downstaging in AJCC staging for breast cancer patients.

Main Methods:

• Utilized Surveillance, Epidemiology, and End Results (SEER) data for hormone receptor-positive, HER2-negative breast cancer patients (T1-3N0-3M0) from 2010-2015.
• Assessed TNM categories, grade, and RS results, focusing on 5-year disease-specific survival (DSS) for patients with low-risk RS not meeting current stage IA criteria.
• Employed 2-sided statistical tests to analyze outcomes.

Main Results:

• Analysis of 154,050 patients revealed that those with RS < 18 and N0-1 disease, not currently staged as IA, exhibited excellent 5-year DSS (97.2%-99.7%), comparable to stage IA patients (P > .05).
• Patients with RS 18-25 showed a slight decrease in DSS for T2N0 (2.3%) and a modest decrease for T1-2N1 (4.2%-6.4%) compared to stage IA.
• A total of 60,886 patients had RS data, with distributions: <11 (22.3%), 11-17 (37.3%), 18-25 (27.1%), and ≥26 (13.3%).

Conclusions:

• A recurrence score (RS) < 18 is associated with excellent 5-year disease-specific survival (DSS) in N0-1 breast cancer patients, irrespective of T category.
• These findings suggest that the AJCC staging system could be refined by incorporating an RS cutoff of 18.
• Further modification of the AJCC staging system is warranted based on the prognostic power of RS < 18.