The clinical rate of growth in patients with breast cancer can be auxometrically classified by identifying the first clinical manifestation observed by the patient (or physician) and by then noting the progression interval that elapsed before treatment and the occurrence of prognostically unfavorable transition events during that interval. These two features can be used to demarcate slow, intermediate and rapid auxometric stages, which approximate the cancer's rate of progression. A fourth stage consists of patients who have systemic or metastatic symptoms before treatment. Within any TNM (tumor-nodes-metastases) stage, degree of nodal involvement or treatment, these four auxometric stages delineate patients with distinctly different prognoses. In particular, the slow auxometric stage can be used to identify a subgroup of patients with excellent 10 year survival and other patients who have good outcomes despite an anatomically unfavorable status. Conversely, the rapid and systemic-metastatic stages identify patients with relatively poor prognoses despite an apparently favorable anatomic status. The auxometric classification is easily used, readily available and involves no technologic expense or risk. By improving the accuracy of anatomic staging, auxometry adds an important refinement to the estimation of prognosis and the evaluation of therapy for patients with breast cancer.