As previously mentioned, older therapeutic approaches to many types of cancers came with unpredictable response rates and significant financial burdens to patients, patient's families, and the healthcare system as a whole. However, with the predictive biomarkers available today, it is possible to make a much more specific selection of therapy with the highest likelihood of effectively treating each individual patient. This directed approach eliminates much of this "trial and error" process and its associated and unnecessary side effects and cost.
But how truly predictive are these type of diagnostic results? According to Harvey et al, patients with breast cancers containing as few as 1-10% of ER positive staining cells will show improvement with estrogen directed hormone therapy. Thus, it is very important that predictive testing be extremely accurate in identifying those patients who will most benefit from these specific treatments.