Widening the target for cancer treatment

Doctors treating cancer patients should aggressively target the area surrounding a tumor during surgery and radiation therapy. That suggestion comes as a result of new studies from Timothy Padera, Rakesh K. Jain, and colleagues (Harvard Medical School, Boston, MA), who report that metastasis occurs through lymphatic vessels in the tumor margin and nearby normal tissue.

Cancer cells can metastasize by escaping a tumor through either blood or lymphatic vessels. Jain's group questioned whether cancerous cells escape through lymphatic vessels within the tumor itself. In various transplanted and spontaneous tumors in mice, and in human tumors, markers of lymphatic vessels were found within the tumors, but functional analysis revealed that these vessels were not draining fluid.

Jain suggests that lymphatic vessels in tumors may collapse from the high pressure exerted by the rapidly proliferating cancer cells. The...