Using a scanner rather than a scalpel could spare hundreds of thousands of cancer patients from risky surgery, a study suggests. Head and neck tumours are treated with chemotherapy and radiotherapy, but then need an operation to visually check whether the growth has gone.

A study on 564 patients, published in the New England Journal of Medicine, showed 80% of them could be spared surgery by scanning instead. And survival rates stayed the same.

Positron emission tomography-computed tomography (PET-CT) uses a radioactive dye that is picked up by rapidly dividing cancer cells. This allows doctors to see if any of the head or neck cancer is still active.

Prof Hisham Mehanna, from the University of Birmingham, told the BBC, "Cancerous cells hide among the dead cells, with PET-CT you can call them out and find out whether they are alive or not. We can now use this new technology to save patients having a debilitating operation and identify those that need the operation rather than give it to everybody." Prof. Mehanna said scanning could help hundreds of thousands of people around the world each year.