ABSTRACT
WHY DO WE NEED MOLECULAR MARKERS?
Breast cancer is a heterogeneous disease in its clinical course and in its molecular features. Cancers with seemingly similar clinicopathologic characteristics may have dramatically different clinical courses. The underlying hypothesis behind tumor marker research is that there is a connection between the molecular and clinical heterogeneity of cancer. Molecules present in or secreted by breast cancer cells may be associated with a particular clinical outcome. A marker may correlate with a clinical outcome without causing it or it may mechanistically contribute to the biologic process that causes the particular outcome: the former could be a useful clinical predictive test; the latter could also serve as a potential therapeutic target.
