Evidence-Based Consensus on the Diagnosis and Treatment of Advanced HER2-Positive and HER2-Low Breast Cancer in Colombia

Background/Objectives: The management of advanced HER2-positive and HER2-low breast cancer is evolving rapidly. This study aimed to generate national, evidence-based clinical recommendations for Colombia, addressing the lack of standardized local guidance. Methods: A systematic literature search (2020–2024) was conducted. The evidence was evaluated using AGREE II, RoB 2, ROBINS-I, and JBI tools. Recommendations were developed using the GRADE approach and a structured modified Delphi consensus process involving 34 national experts. Results: A total of 22 clinical recommendations were formulated. These address HER2 quantification and reporting, first-line and subsequent-line therapy, and management of brain metastases. Five recommendations (23%) were classified as strong, supported by high-certainty evidence, while 17 (77%) were conditional, reflecting the need for adaptation to local contexts and resource availability. Conclusions: This consensus provides updated, context-specific clinical guidance to optimize the care of patients with advanced HER2-positive and HER2-low breast cancer in Colombia. The recommendations are designed to standardize care, improve patient outcomes, and promote equitable access to innovative therapies within the Colombian healthcare system.