London, Aug 13 (IANS): Combining chemotherapy with a drug that blocks part of the immune system from going into overdrive might help prevent cancer coming back in some people, says a new study.

Cancer-killing action of chemotherapy can trigger a swarm of wound-healing, white blood cells to cluster around blood vessels in a treatment-hit tumour, the researchers found.

These cells repair tissue damage and build new blood vessels, a process that sometimes helps the tumour to grow again after treatment.

But by treating mice with cancer with a drug that stops these repair cells from working, the researchers markedly reduced the speed at which tumours grew back after chemotherapy.

"Scientists already knew that the body's drive to heal itself can sometimes backfire when the immune system reacts to tissue damage,” said lead researcher Claire Lewis, professor at University of Sheffield in England.

“Our research shows that treating tumours with chemotherapy can activate this part of the immune system, and this then helps tumours re-grow afterwards,” Lewis noted.

"But combining chemotherapy with a drug that switches off this part of the body's repair system, slowed the growth of tumours after chemotherapy,” Lewis said.

The drug that the researchers tested is already used in patients for other reasons, such as bone marrow transplants.

However, clinical trials of patients are needed to confirm if the drug could help cancer patients after chemotherapy.

The findings published in the journal Cancer Research could be particularly significant for patients who cannot have surgery and, therefore, need chemotherapy to help them live for as long as possible.