Biomarker-Guided Decisions for Breast Cancer Therapy
According to American Society of Clinical Oncology Clinical Practice Guideline, in addition to ER, progesterone receptor and EGFR-2, there is sufficient evidence for clinical utility of the biomarker assays Oncotype DX, EndoPredict, PAM50, Breast Cancer Index, urokinase plasminogen activator, and plasminogen activator inhibitor type 1 in specific subgroups of breast cancer (Harris et al. 2016). No biomarker except for ER, progesterone receptor, and EGFR-2 was found to guide choices of specific treatment regimens, which should also consider disease stage, comorbidities, and patient preferences.
Research is needed in all areas in the guideline to continue to refine and redefine clinical utility of specific biomarkers. Inclusion of biomarker investigations at the beginning of clinical trials during conception and design and prospective or prospective-retrospective studies that validate the clinical utility of biomarker candidates are important for enabling selection of therapy for early-stage invasive breast cancer. Research also is needed to better understand the impact of age, race/ ethnicity, and health disparities on the prognostic and predictive value of biomarker candidate.
Concluding Remarks and Future Prospects of Breast Cancer Biomarkers
Numerous biomarkers of breast cancer have been investigated but few have shown practical usefulness in management of patients. There is a need to start consolidating the pathways and analyzing overlapping/cooperative natures of molecules from pathways. Potential usefulness of the cytoplasmic kinases and coactivators, which may act as coregulators in the action of estrogen receptor, is likely to accelerate the development of the next generation of biomarkers for the surveillance, prognosis and therapeutic decisions for cancer.