Interpreting and integrating risk factors for patients with primary breast cancer

The term risk factor has different meanings in different contexts. Some factors may be patient specific (e.g., race, age, socioeconomic status, and environment), while others may be disease specific (e.g., biomarkers measured on tumor specimens, serum, and bone marrow). These factors have several potential clinical uses, including diagnosing a disease or assessing the risk of developing a disease, estimating prognosis for patients diagnosed with a specific disease who receive no therapy, predicting response to a particular therapy, monitoring response to therapy during a treatment course, and identifying targets of opportunity for new therapies. This article focuses on prognostic and predictive biomarkers and provides guidelines for interpreting published reports about these biomarkers. Application of these guidelines to the assessment of micrometastases in bone marrow of patients with breast cancer yields the conclusion that standardized techniques that are sensitive and reproducible for detecting micrometastases are needed before we can evaluate their prognostic significance.