Recommendations for adjuvant and palliative treatment in breast cancer patients are based on a clinician's estimated risk assessment for relapse, death, and the likely benefit of systemic treatment. However, predicting the absolute benefit of systemic therapy for an individual woman with breast cancer is a complex issue. Western patient-based prediction system may not be suitable for Asian breast cancer patients who are associated with younger age and worse prognosis than Western patients.
For the individualized treatment, there are several ways of approach for the breast cancer patients. First, screen the patients for the specific targets with available target-specific drugs. The good model is the anti-HER2 drug treatment of the HER2 amplified or over-expressing patients. Second, for chemotherapeutic agents, trials to use the biomarker in predicting poor prognosis from chemotherapy resistance are under study. These markers are being studied using polymorphism, copy number change, genomics study or combination of these. There is no specific data yet whether there are ethnic differences in chemotherapy resistance or biomarker expression. Third, use high-throughput technology to select the patients to better determine which patients group really needs specific treatment. The best example is the MINDACT trial. One possible limitation is that the biomarker may differ between early-stage and advanced stage. In current trials, biomarkers are determined from the original diagnostic tissues and may not reflect the relapsed tumor status, and thus hamper the decision making for the personalized treatment.
As there are so many developed targeted agents, it is a real issue how we can combine the targeted agents or to find the best chemotherapy partner to targeted agent to a specific patients. In lung cancer, the BATTLE trials are being done toward realizing personalized cancer therapy by integrating real-time molecular markers. Like this, translational research and biomarker-driven clinical trials are warranted for the Asian breast cancer patients for the personalized treatment.