Prognostic and Predictive Factors for Breast Cancer: Translating Technology to Oncology

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Abstract
In medical school, we were taught that clinical deci- sion making requires a consideration of the balance of benefits and risks to provide optimal care for the patient. As we train and then practice medicine, understanding and conveying the risks and benefits of a given treatment are constantly refined by personal experience, interactions with patients, our colleagues and experts in the field, and availability of evidence derived from well-designed and -analyzed clinical trials. Managementofpatientswithbreastcancerisagreatil- lustration of this complex and iterative process. In the pre- ventive, primary care, and adjuvant settings, decisions are made for individuals based on our hope that, in general, we help more patients than we harm. For women with rel- atively low risk of developing metastatic disease, such as those with high-risk but benign breast findings or women withsmall,hormone-dependent,node-negativebreastcan- cers,weneveractuallyknowifwehavehelpedanindividual patient. Indeed, a majority of such patients will not recur despite our care, not because of it. On the other hand, treatment of patients with metastatic disease, although ultimately almost always associated with a tragic outcome, canbeextraordinarilyrewarding.Inthissetting,wecanob- serve a highly symptomatic patient regain her quality of life as a clear-cut consequence of judiciously applied local and systemic therapies, including endocrine and chemothera- piesand,morerecently,noveltherapysuchastrastuzumab. Arguably, prognostic and predictive factors have been of value to help individualize therapy of breast cancer more than for any other solid tumors. The substantial benefits of adjuvant systemic therapy have been well documented for over 30 years.1,2 Furthermore, it is a disease for which dis- parate therapies are beneficial in different subgroups. For example, it appears that adjuvant chemotherapy reduces the annual odds of recurrence by approximately 25% to 30% for all patients.2 In those with an initially poor prog-