The discovery follows the announcement that the UK’s Academy of Medical Royal Colleges has listed 40 treatments that are unnecessary and shouldn’t be given routinely. As well as chemotherapy for advanced cancers, the list includes x-rays for lower back pain, regular scans for terminally ill patients and routine checks for patients after a cataracts procedure or other common and routine surgery.

Announcing the list, AMRC chairman Prof Dame Sue Bailey said patients—and doctors—should think twice before having tests or treatments, and question whether they really were necessary. “Patients should ask ‘what would happen if I do nothing?’” she said.

The AMRC, which represents all 21 medical royal colleges, is planning to extend the list to around 150 unnecessary treatments.

In the survey of around 5,000 doctors, the vast majority who admitted ordering a drug or procedure they knew was useless were driven by a fear of litigation, and, in some cases, because the patient demanded it.

Around 20 per cent admitted prescribing an antibiotic, 16 per cent ordered x-rays and 14 per cent CT scans or blood tests that they knew were unnecessary.