Biomarkers are biological molecules found in blood, other body fluids, or tissues. They are signs of a normal or abnormal process or of a condition or disease. In breast cancer, common biomarkers include hormone receptors like estrogen (ER) and progesterone (PR), and human epidermal growth factor receptor 2 (HER2). These markers help doctors understand how aggressive the cancer is and how it might respond to certain treatments.

The eighth edition of the TNM staging system integrates biomarkers into the staging process. This is a significant advancement from previous editions, which focused solely on anatomic factors. By including biomarkers, the staging system provides a more detailed picture of the cancer, helping to predict outcomes and tailor treatment plans. This integration marks a step towards more personalized and precise cancer care.

Biomarkers play a crucial role in determining the best treatment options for breast cancer patients. For instance, cancers that are HER2-positive can be treated with targeted therapies like trastuzumab. Similarly, ER-positive cancers may respond well to hormone therapies. By understanding a tumor's biomarker profile, doctors can choose treatments that are more likely to be effective, improving the chances of a successful outcome.

Biomarkers are revolutionizing breast cancer diagnosis and treatment by enabling more personalized care.