New study suggests the toxic medication switches on a repair mechanism in the body which ultimately allows tumours to grow back stronger

New research shows that chemotherapy could actually cause cancer to spread and become even more deadly.

A new study by scientists at New York’s Albert Einstein College of Medicine suggests that the widely used cancer treatment, often the first option for breast cancer patients, can trigger more aggressive tumours to develop.

The Telegraph reports:

Around 55,000 women are diagnosed with breast cancer in Britain every year and 11,000 will die from their illness.

Many are given chemotherapy before surgery, but the new research suggests that, although it shrinks tumours in the short term, it could trigger the spread of cancer cells around the body.

It is thought the toxic medication switches on a repair mechanism in the body which ultimately allows tumours to grow back stronger. It also increases the number of ‘doorways’ on blood vessels which allow cancer to spread throughout the body.

Dr George Karagiannis, of the Albert Einstein College of Medicine of Yeshiva University, New York, found the number of doorways was increased in 20 patients receiving two common chemotherapy drugs.

He also discovered that in mice, breast cancer chemotherapy increased the number of cancer cells circulating the body and in the lungs.

Dr Karagiannis said women could be monitored during chemotherapy to check if cancer was starting to circulate and doorways were emerging.