Capita has admitted that 4,508 letters about screening results have been delayed this year and that 43,200 women who should have received invitation and reminder letters about cervical screening were sent one or the other 'but not both'.
GP leaders warned that patients may have been put at risk and demanded that Capita be stripped of its NHS contract after the latest in a string of problems with primary care support.
In a letter to NHS England chief executive Simon Stevens, the BMA expressed 'extreme concern' about 48,500 women not receiving key information about cervical cancer screening.
GPC chair Dr Richard Vautrey said: 'This is an incredibly serious situation, and it is frankly appalling that patients may now be at risk because of this gross error on the part of Capita. Some women will now be left extremely anxious because they have not received important correspondence, particularly letters about abnormal smear test results that need urgent follow up. This has been caused solely by Capita’s incompetence.'
Dr Vautrey said that because of the nature of cervical screening, many patients were reluctant to attend - and that reminder letters were 'crucial' to boosting uptake.
The GPC chair added: 'Since it took responsibility for GP backroom functions three years ago, Capita‘s running of these services has been nothing short of shambolic and after repeated warnings from the BMA and government, this is now clear evidence that its failings have put patient safety – and possibly lives – at risk.
'It is ultimately NHS England that bears overall responsibility and it must now take this service back in-house. As the body which commissioned Capita to take on this work, despite clear warning signs that it was not up to the job, NHS England must shoulder the blame for this dreadful situation; you cannot outsource responsibility.'
The National Audit Office has criticised NHS England over its 'high-risk' decision to outsource primary care support services to Capita in a £330m seven-year deal - warning the move left patients in danger of serious harm.
The BMA said it had been assured by NHS England that patients affected by the cervical screening correspondence failure had been written to and that GP practices had been informed.
The union said it was 'now informing its GP members, alerting them to the situation and preparing practices for the very understandable concerns and queries that patients are going to have'.
An NHS England spokesperson said: 'Capita has alerted NHS England to an administrative failure in its processing of cervical screening, which means some women have not received invitation, reminder and result letters when they should have.
'Every woman’s case is being reviewed, but there is no current evidence that this incident has led to harm to the women involved, and our priority now is to ensure that anyone affected by this incident is contacted, and knows how to get checked if they are due a cervical screen.'
A statement released by Capita says the 'risk to women of this incident is low and there is no current evidence of harm'. The company has apologised to women affected and says it has appointed a team of auditors to 'carry out a detailed review into operational systems and processes' in its primary care support service.
Capita added: 'We have investigated the precise circumstances around this incident, and it is clear that the correct process for uploading, organising and checking datafiles was not properly followed. When the problem was discovered, it was not immediately escalated to senior leadership, or NHS England, by the individuals responsible.
'Capita is investigating the managerial handling of the matter and taking appropriate disciplinary action. Additionally, a senior executive responsible for this contract has already left Capita.'