More than 3,000 operations have been cancelled by the NHS in the first two weeks of this month as an "unprecedented demand" takes its toll.
Figures show 3,113 elective operations were cancelled in that period, up by almost half since 2012.
In terms of operations classed as urgent 161 were cancelled in the two-week period, with some having been cancelled twice or more.
The figures, highlighted by Labour, show the repercussions of A&E departments under severe stress and a lack of beds for patients in need, a consultant and member of the Royal College of Surgeons said.
Shafi Ahmed said: "There is currently unprecedented demand on the NHS resulting in more cancellations of planned surgical operations.
"As a practising surgeon, looking after cancer patients, it is very difficult to have to tell a patient who has prepared themselves for a major procedure that their operation has been cancelled for non-clinical reasons.
"To reduce pressures on hospitals and to keep a flow of patients coming in and leaving hospital, we need to manage the number of available beds more efficiently. To achieve this, we need to reduce unnecessary admissions and visits to A&E and improve community care.
Mr Ahmed said improvements are also required regarding discharge arrangements, to avoid patients staying in hospital longer than necessary, and called for ring-fencing of beds for high dependency care to be considered.
Labour's shadow health secretary Andy Burnham said: "This is yet another sign that, under David Cameron, the NHS is simply not working.
"Standards of patient care are slipping by the week and now more and more people get ready for an operation only to face a last minute postponement.
"The chaos in A&E is spreading through the NHS. Hospitals are in danger of becoming overwhelmed as the Government takes social care away from older people and makes it harder to see a GP. These cancellations help to explain why operation waiting lists are at a six-year high."
He pledged Labour would invest an extra £2.5 billion in the NHS each year, resulting in 20,000 more nurses and 8,000 GPs.
The Department of Health told the Sunday Times the figures show "the proportion of cancelled operations remains remarkably stable over many years", adding that more operations are being carried out amid an ageing population.