fig3

Figure 3. The clinical implications of tumor heterogeneity. Cancer diagnosis is commonly based on tumor biopsy, which is usually a small fraction of the total tumor mass and does not represent all subclones inside the tumor. Initial diagnosis is made based on the tumor biopsy. After the first-line treatment, dominant clones can be killed successfully whereas resistant clones persist and drive tumor progression. Metastasis may develop from the resistant clones that survive the initial treatment. New diagnosis needs to be made in order to apply the second-line treatment