Clerical blunder gave all-clear to 11 women with signs of breast cancer

Eleven women with early signs of breast cancer were mistakenly given the all-clear by an NHS breast screening service after their notes were put on the "wrong pile", an investigation has found.

The blunder at the West London Breast Screening Service at Charing Cross Hospital meant women who should have been recalled for further checks were sent the wrong letter telling them they did not need another screen until the routine interval of three years.

One woman suffered a delay of 21 months before she was alerted to her cancer. Others waited weeks or months in ignorance that they had the disease. All have now been offered treatment.

The failure is the worst to affect the national breast screening service since 85 women had their cancer missed or their diagnosis delayed by the East Devon breast screening service in Exeter. That scandal, which came to light in 1997, led to tighter checks on the national screening service. The West London Service, one of the largest in the country in screening 40,000 women a year, was suspended in June because it failed to meet those standards.

Three investigations of the imaging directorate have been made in the past three years, because of allegations of mismanagement and concerns over patient safety. Last week Nuala Martin, the manager, announced her resignation.

A spokeswoman for the Hammersmith Hospitals NHS Trust, which manages the screening service, said yesterday that breast screening would not restart until managers were confident the problems had been solved.

The mistake is being blamed on the management systems, which led to notes being misfiled. The error was discovered last October when a woman moved to a new health authority area where doctors found a note in her file saying she should be recalled for reassessment. Instead, the woman had been sent a routine three-year recall letter.

Hospital managers immediately ordered a check of 174,000 separate screening episodes of 104,000 women going back to 1993, which was done by PriceWaterhouseCoopers. They found 123 women had been sent the wrong letter. Of these, 11 women were found to have developed cancer and 35 were checked and cleared. A further 77, for whom mammogram films were missing, have been invited back for a repeat screen. The Commission for Health Improvement, the Government NHS watchdog, is investigating the management of the service to determine what happened.

John Cooper, chief executive of the trusts, said: "We deeply regret the considerable distress caused to these women and we have tried to do everything we can to ensure they receive appropriate treatment."