Breast Screening – Is it worth it?

Choosing whether to have breast screening is a complex decision for any woman, balancing the risks of benefit and harm. The program was introduced 30 years ago for those aged 50-70, using 3 yearly mammograms, which use X-ray imaging to find breast cancer before a lump can be felt. However, it wasn’t until a review in 2012 that women were given proper information about the downside instead of the patronising ‘have screening, it’s good’ government line. The Marmot review found that for every 1,000 women screened over 20 years, about 5 breast cancer deaths are prevented at the expense of around 17 women being diagnosed and treated for a cancer that would never have caused them any problem. Furthermore, more than 200 women will experience significant psychological distress, anxiety and uncertainty because of false positive findings. And to make matters more confusing, the overall death rate from ‘all causes’ does not improve with screening. The lives saved from screening are balanced by the lives lost through overtreatment from X-ray exposure, surgery, chemotherapy and radiotherapy. In addition, screening doesn’t pick up all cancers and some women die at the same age of unrelated causes whether they had screening or not.

In 2017, the Nordic Cochrane Centre published a cohort study that found that screening did not reduce the number of late stage tumours (those bigger than 2 cm) and that screening is unlikely to reduce breast cancer mortality or lead to less invasive treatment. It found 1 in 3 breast cancers detected in women by screening are likely to be over-diagnosed and over-treated, which costs the NHS a significant sum but makes private practice very lucrative. Independent expert groups in Switzerland and France have recommended that breast screening be stopped or reduced substantially. And the American Cancer Society recommends less frequent screening of a narrower age group. In England, the NHS was planning to extend the screening age range from 47-83 but has inadvertently cut it by failing to send out 50,000 final mammogram invites a year for 9 years. Could this have done more good than harm? And should women queue for their missed screen or let it be?

Health Secretary Hunt rightly apologised but then claimed that 135-270 lives may have been shortened by the screening recall failure. Medical negligence lawyers such as Leigh Day are licking their lips but – when the evidence is forensically dissected – it will be near impossible for any woman to prove that her life may have been shortened by the error. For a start, there is no current evidence that missing a single screen at age 68-70, at the end of a 20 year screening programme, will harm you. Hunt’s guess comes from the most optimistic estimate that 1 in 1400 women has an early death from breast cancer prevented per screen. Hunt and Public Health England (PHE) appear to have divided 450?000 by 1400 to get 321, then factored in the fact that 30% of women decide not to be screened so 225 lives may have been shortened, but make it a range (135-270) to make it clear it’s a guess and individual harm is hard to prove. However, given that the government has spent 30 years simplistically telling women that ‘screening saves lives’, it would be hard to perform a volte farce and argue that not screening doesn’t shorten lives, even if the evidence – particularly for older women – is lacking.

The initial error may have been in computer programming, setting the wrong age parameter, but the fact that it wasn’t acted on for 9 years, despite some hospitals raising concerns, has led PHE and Hitachi to blame each other. 50,000 missing mammograms a year sounds a lot, but given there are 79 screening units in England, only a dozen women a week in the older age group were not being screened. The NHS has gone into full panic mode. The emergency phone line (0800 169 2692) had more than 8000 calls on its first day and PHE has promised to contact the 309?000 women they think are still alive by the end of May, with the aim of providing mammography to all who want it by the end of October. Breast screening units across the country may have to arrange thousands of additional appointments and many are already stretched to the safe limit due to staff shortages. This could be a recipe for more errors and more litigation. As the Nordic Cochrane website observes, the tremendous advances in breast cancer treatment make early diagnosis through screening less important to survival; ‘It no longer seems beneficial to attend for breast cancer screening.’ By opting out of screening, a woman will lower her risk of being labelled and treated for early breast cancer with no benefit to her quality of life, or life expectancy. Many women will still choose to be screened but for the 800 or so who would have been over-diagnosed, the NHS error may have been a blessing in disguise.