Prognostic Features and Clinical Outcomes Across Breast Cancer Subtypes Defined by Hormone Receptor and HER2 Status: A Literature Review

Abstract

Introduction: Hormone-responsive breast cancer biologically varies from hormone-unresponsive breast cancer in treatment response. Hormone-responsive breast cancers are characterized by estrogen (ER) and progesterone (PR) receptors that, upon activation, alter gene expression and promote tumor growth. The presence of these receptors highlights ideal targets for treatments that block or lower hormone levels. In contrast, hormone-unresponsive breast cancers lack these receptors, exhibit insensitivity to endocrine therapy, and display poorer prognoses. Understanding the differences between hormone-responsive and unresponsive breast cancer presents crucial implications for developing effective treatment strategies, improving patient outcomes.

Methods: A literature review was conducted using PubMed to identify English-language, peer-reviewed studies published between 2014 and 2025 examining breast cancer subtypes based on ER, PR, and HER2 status. Clinical trials, population-based cohort studies, and subtype-specific analyses evaluating prognosis, metastatic potential, or treatment responsiveness were included. Fifteen studies met the inclusion criteria and were included in the qualitative synthesis.

Results: Hormone receptor-positive tumours expressing ER and PR demonstrated the most favourable outcomes, with slower metastasis and lower proliferative activity compared to receptor-negative tumours. Triple-negative breast cancer (TNBC) demonstrated the most aggressive biological course, characterized by increased metastatic potential and reduced responsiveness to endocrine therapy. Evidence from recent clinical trials indicates that in advanced TNBC, therapeutic benefit is primarily limited to immunotherapy-based combination strategies. While HER2 expression reflects a more aggressive biology, its presence enables targeted therapeutic intervention associated with improved patient outcomes.

Discussion: Differences in subtype biology, metastatic behaviour and treatment responsiveness highlight the importance of hormone receptor status and subtype classification in guiding the clinical management of breast cancer.

Conclusion: Hormone receptor status is a strong determinant of prognosis and treatment responsiveness across breast cancer subtypes, with HR-positive tumours demonstrating more favourable outcomes and TNBC exhibiting the most aggressive disease course. These findings emphasize the need to refine therapeutic strategies and guide the development of effective treatment options and molecular targets to improve outcomes across all breast cancer subtypes.