DNA strands forming a woman's silhouette symbolizes personalized breast cancer treatment.

Decoding Breast Cancer: How Molecular Biology Can Improve Prognosis

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Avery Sinclair in Health & Wellness August 2025 • 4 min read.

"Unlocking the secrets of breast tumors to tailor treatments and improve outcomes for women worldwide."


Breast cancer is a global health challenge, being the most common cancer among women worldwide. Researchers are working tirelessly to understand what triggers the disease, identify key players in its progression, and develop effective, less toxic interventions.

These efforts have led to significant improvements in overall survival, particularly for specific subsets of breast cancer. Treatments and care for breast cancer patients have reached a high standard, but there's still an urgent need to distinguish between tumors requiring aggressive treatment and identify the best therapeutic options tailored to each patient.

Achieving this requires successfully translating the wealth of information clarifying breast cancer biology into clinical practice. Scientists and clinicians must work together, using multidisciplinary approaches to reach this important goal.

Gene Expression Profiles: A New Era of Classification

DNA strands forming a woman's silhouette symbolizes personalized breast cancer treatment.

Traditional methods of classifying breast cancer are evolving thanks to large-scale gene expression profile (GEP) studies. These studies have revealed that breast cancer isn't a single entity but comprises at least four major subtypes: luminal A (LBC-A), luminal B (LBC-B), HER2-positive, and triple-negative/basal-like. This classification is now reinforced by genomic data, demonstrating different recurrent genomic alterations in each subtype.

Luminal breast cancer (LBC) is the most common subtype in the Western world, accounting for over 60% of diagnoses. Clinically, factors like estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki67 expression help distinguish LBC-A (ER+ and/or PR+, HER2-, low Ki67) from LBC-B (ER+ and/or PR+, HER2- or HER2+, high Ki67).

  • Hormone Therapy: Targeted at ER+ and/or PR+ cancers to block hormone-fueled growth.
  • Chemotherapy: Traditional cytotoxic drugs to kill rapidly dividing cancer cells.
  • Targeted Therapies: Designed to attack specific vulnerabilities in cancer cells, like HER2.
This refined classification has therapeutic implications. Based on the expression of these markers, patients receive hormone, chemo, or targeted therapies. LBC-B has a higher rate of early recurrence and a worse prognosis than LBC-A, posing challenges for clinicians in choosing the optimal therapy. Validating and introducing clear biomarkers to guide treatment decisions for LBC-B remains a priority. The classification also has prognostic relevance, with triple-negative and HER2+ BC having a more aggressive progression. These molecular characteristics are present in early-stage and in situ lesions, suggesting early diagnosis can identify and remove potentially malignant tumors that need aggressive treatment.

The Future of Breast Cancer Treatment: Personalized and Timely

The key to further improving breast cancer treatment lies in identifying cancers that need aggressive treatment and discovering the most appropriate treatment for each patient. This approach reduces the risk of overtreatment while maximizing the effectiveness of therapy.

Studies suggest that breast cancer diagnosed before age 40 requires more accurate classification. Young age at diagnosis is an independent factor associated with higher risk of relapse and death. Differences in the mammary stroma and changes during pregnancy and breastfeeding may contribute to the unique biology of breast cancer in younger women.

Integrating sequencing and gene expression profile studies with high-throughput functional analyses is crucial for identifying genes and pathways that each tumor type is dependent on. Targeting these pathways at the right time, such as during surgery, may significantly impact disease-free and overall survival. Better models that recapitulate the biology of breast cancer in younger women and greater collaboration between clinicians and preclinical researchers are needed.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.12688/f1000research.8158.1, Alternate LINK

Title: Molecular Biology Of Breast Tumors And Prognosis

Subject: General Pharmacology, Toxicology and Pharmaceutics

Journal: F1000Research

Publisher: F1000 Research Ltd

Authors: Gustavo Baldassarre, Barbara Belletti

Published: 2016-04-21

Everything You Need To Know

1

How have gene expression profiles changed how breast cancer is classified?

Gene expression profile (GEP) studies have revolutionized breast cancer classification by revealing that it comprises at least four major subtypes: Luminal A (LBC-A), Luminal B (LBC-B), HER2-positive, and triple-negative/basal-like. This classification is reinforced by genomic data, demonstrating different recurrent genomic alterations in each subtype, allowing for tailored treatment approaches.

2

What distinguishes Luminal A breast cancer from Luminal B breast cancer, and why is this important?

Luminal breast cancer (LBC), the most common subtype, is further divided into LBC-A and LBC-B based on factors like estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki67 expression. LBC-A is typically ER+ and/or PR+, HER2-, with low Ki67, while LBC-B is ER+ and/or PR+, HER2- or HER2+, with high Ki67. This distinction is crucial because LBC-B tends to have a higher rate of early recurrence and a worse prognosis than LBC-A.

3

What are the main treatment strategies used to combat breast cancer, and how are they targeted?

The primary treatment strategies involve hormone therapy for ER+ and/or PR+ cancers, chemotherapy to kill rapidly dividing cancer cells, and targeted therapies designed to attack specific vulnerabilities, such as HER2. These approaches are tailored based on the specific subtype and expression of markers in the tumor. While surgery and radiation therapy are commonly used treatments, they are not detailed in this context.

4

What are the potential implications of accurately identifying cancers that need aggressive treatment early on?

The ability to distinguish between tumors that require aggressive treatment and identify the best therapeutic options tailored to each patient significantly reduces the risk of overtreatment while maximizing therapy effectiveness. Early diagnosis using molecular characteristics can identify potentially malignant tumors that need aggressive treatment, improving overall outcomes.

5

What are some outstanding challenges and potential future advancements in breast cancer treatment?

While advancements have been made, validated biomarkers are still needed to guide treatment decisions, particularly for LBC-B, which presents challenges due to its higher recurrence rate and worse prognosis. Future advancements likely involve further personalizing treatment plans based on a deeper understanding of individual tumor biology and developing new targeted therapies to address specific vulnerabilities.

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