fig3

Figure 3. Origin of metastases. (A) TNM staging, closedly related to Halsted-Meyer theory of breast cancer progression, suggests that remote metastases arise late in the progression of the primary tumor, with disseminating cells first traveling to the lymph nodes; (B) the cancer dormancy hypothesis suggests that tumor cells disseminate early to remote sites and are then forced into a dormant state by immune surveillance. These two alternatives can be distinguished in part by examining cell genomes to trace cell lineages