Surge in cancelled operations in England
More than 20,000 NHS operations were cancelled at the last minute between January and March in England.
It is the highest proportion of operations - one in every 100 - that have been cancelled in two years.
Hospitals should offer an alternative date or private treatment within 28 days, but the proportion not being seen is the highest in a decade.
NHS England said cancellations were low in light of the "unprecedented" demand on the health service.
The NHS figures show 20,464 operations out of more than 1.9 million were cancelled in the quarter.
It compared with 17,868 at the same point in the previous year.
The figures also show 1,787 - just under 9% - of those patients were not seen within the 28 day limit.
Plymouth Hospitals NHS Trust had the most cancellations with 648.
An NHS England spokesman said: "Cancellations should be avoided wherever possible as we recognise the concerns that patients face when this happens.
"However, the level of cancellations in this quarter has remained low in the context of the millions of operations performed in the NHS each year, and the unprecedented level of demand we have seen across the whole health system this winter."