08 April 2016
Vol 352, Issue 6282

About The Cover

Cover image expansion

COVER Artist's interpretation of tumor cells in transit from the primary tumor (background) to the site of metastasis (foreground). After entering the vasculature (depicted as red snaking branches), circulating tumor cells—shown here in a much greater number than would occur in a cancer patient—eventually exit at the metastatic site. Recent research on metastasis, a leading cause of cancer mortality, is highlighted in a special section beginning on page 162.
Illustration: Valerie Altounian/Science