Volume 4, Issue 1, Pages 4-6 (July 2003) Evidence emerges for early metastasis and parallel evolution of primary and metastatic tumors  Joe W Gray  Cancer Cell  Volume 4, Issue 1, Pages 4-6 (July 2003) DOI: 10.1016/S1535-6108(03)00167-3

Figure 1 Schematic representation of serial and parallel models of tumor evolution to metastasis In one model (left branch), progression to metastasis occurs through clonal evolution so that most properties of the primary tumor will be found in disseminated metastatic cells. Another model (right branch) suggests that cells that form metastatic disease separate early from the primary tumor and evolve more-or-less independently from the primary tumor. Cancer Cell 2003 4, 4-6DOI: (10.1016/S1535-6108(03)00167-3)