Millions of people missed out on potentially life-saving scans when non-Covid-19 services ground to a halt during the pandemic.
In England, some 4.4 million fewer scans were performed between April and September compared to the same period in 2019.
One in seven people are now waiting more than three months for a scan as the National Health Service attempts to clear the backlog, saying some services are now back to the same levels as last year.
But the period of inactivity has left a backlog that could leave many people presenting at hospital in a worsened condition.
Jody Moffatt, head of early diagnosis for Cancer Research UK, said, ” There is a cohort of patients out there that have not been diagnosed yet. Those patients could be diagnosed with a more aggressive, later-stage cancer.”
The British Institute for Radiology said the fall in the number of scans was because non-essential appointments were canceled at the end of March.