GPs and patients need more reliable information about trust waiting times, MPs have warned.
Waiting times at seven trusts investigated by the National Audit Office (NAO) were not backed up by documents, and a further 26% were wrong.
The public accounts committee (PAC) claimed that the Department of Health (DH) "cannot be sure that the waiting time data NHS England publishes is accurate", and has called for independent auditing of the data.
NHS England allows "flexibility" in how trusts manage patient waiting times, and does not ensure that the data is consistent or accurate.
PAC said this has had the "unintended consequence" of creating variations between trusts on the number of cancellations patients can make before being referred back to their GP.
At the launch of a PAC report on the reliability of information on NHS waiting times, Margaret Hodge, chair of the public accounts committee said: "If patients cannot be confident of accurate comparable data on the performance of hospitals they cannot exercise choice.
"Both GPs and their patients need reliable and comparable information about the waiting time performance of individual trusts so that they can make an informed choice about where to be treated."
Dr Mark Porter, chair of the British Medical Association Council, said: "Ministers need to ensure data collection is consistent and reliable. However a rise in the number of private providers and the fragmentation of services, resulting from the government's top down reorganisation, has made this harder, not easier to achieve.
"What matters most is that doctors are able to treat every patient based on their clinical need and ministers must work with clinicians to improve the whole patient journey - from the care they receive from their GP, to a referral to a specialist. By involving those who deliver the service, and listening to their concerns, it is more likely that targets will be realistic, achievable and most importantly, meaningful for patients."
Hodge warned that the Choose and Book appointment system has been "underused" by patients and professionals.
She said: "We are sceptical about the NHS' ability to ensure that the replacement system, e-Referrals, will be used any more fully."
NHS England has been tasked with building up confidence and utilisation of the new system by PAC.
Patients have the right to have elective pre-planned consultant-led care within 18 weeks of being referred for treatment.
The performance standards mean that 90% of patients admitted to hospital, and 95% of other patients, should have started treatment within 18 weeks of being referred.
In April 2013, NHS England introduced zero tolerance of any patient waiting more than 52 weeks.