When the body works to heal itself after surgery to remove a breast cancer tumor, according to new research, it might weaken the immune system — leaving the cancer more likely to recur.

“Without immune control, nests of cancer cells scattered at distant sites in the body can begin to proliferate and generate tumor colonies,” said Robert Weinberg, a biologist at the Massachusetts Institute of Technology and one of the authors of the paper published in Science Translational Medicine Wednesday. “Precisely this type of response may occur after a woman has had her primary tumor removed by surgery, but has breast cancer cells already scattered throughout the body that remained undetectable because they were kept under control by the immune system.”

Weinberg is quick to point out that the research is based on laboratory mice rather than humans. But the results are intriguing, according to his team, because they could help explain why breast cancer often recurs after surgery to remove a tumor.

Weinberg and his colleagues studied two groups of mice. One group was surgically wounded, and both groups were injected with cancer cells. The immune systems of the uninjured mice, they found, were much more successful than those of the injured mice at fighting off the tumor cells.

The findings also suggested a new course of treatment. Mice that they treated with an anti-inflammatory drug after the surgery developed much smaller recurring tumors than the other mice — so, the researchers suggested, it might be effective to treat cancer patients with anti-inflammatory drugs after surgery.