Cancer cells may be protected post-chemo

BOSTON, Nov. 1 (UPI) -- After chemotherapy, some healthy cells may be shielding cancer cells, a U.S. researcher says.

Michael Hemann of the Massachusetts Institute of Technology says he and his colleagues were surprised to find lingering tumor cells that resist treatment and seed disease resurgence may persist because they are being protected by neighboring healthy cells.

Their study using mice with lymphoma, published in Cell, suggests this may be why some patients who initially respond well to chemotherapy redevelop cancer -- sometimes years later.

"It's a surprising finding, but it's consistent with organ homeostasis," Hemann says in a statement.

He explains an organ maintains itself by responding to stressful conditions.

"In this case, the stress response is to chemo. The chemotherapy kills tumor cells while it elicits stress responses that protect a subset of tumor cells in select locations from drug action," he says.

He suggests -- if the study findings are relevant in human cancer -- combining therapies may reduce the chances of cancer reoccurrence.

"The approach to cancer is usually single agents," Hemann says. "Our data suggest that a combination of DNA damaging chemotherapy or radiation plus treatments designed to block pro-survival pathways would be the most potent therapy."