How Cancer Moves (IMAGE) University of Southern California Caption Metastasis in progress: The human circulatory system in many ways resembles an elaborate highway system. In the artist's rendering above, we get a sense of the roughly 100,000 mile length of an adult's system of blood vessels. In this maze, Professor Paul Newton is forecasting the many detours of a circulating tumor cell (CTC). Credit Illustration by Yang Liu. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.