No screening is better for women with low breast cancer risk, finds study

This article was taken from: https://www.theguardian.com/society/2018/jul/05/no-screening-better-for-women-with-low-breast-cancer-risk-finds-study

By Sarah Boseley

Number of women put through unnecessary tests would reduce if screening done by risk, find UCL researchers

Women who are at lower risk of breast cancer – about a third of the population – would be better off not being invited for NHS screening for the disease, according to new research.

Researchers at University College London have found in a modelling study that screening according to risk would reduce the number of women who are put through unnecessary tests and treatment for breast cancer without substantially increasing the numbers who are missed.

Only 72% of women invited to breast screening actually go. The UCL researchers say that genetic testing and informing each women of her individual risk could result in just the 70% at highest risk being screened, while the low risk 30% are not given an invitation to have a mammogram every three years as they are now.

Selective screening would do more good than harm. It would not only reduce over-diagnosis and stress to women, but would be more cost-effective for the NHS, they say.

We already screen by risk, but that risk is age alone, said Dr Nora Pashayan of the UCL department of applied health research, lead author of the study in the journal JAMA Oncology. We now know there are 300 genetic variants linked to breast cancer and that a combination of lifestyle factors and reproductive history also play a part – smoking, obesity, not having children or not breastfeeding all increase risk, she said.

Each woman should soon be able to go to her GP and get a genetic test that will tell her whether she is in the low risk 30% who would not need screening – but not just yet. “The technology is available but the test is not yet available on the NHS,” said Pashayan. “You can’t go tomorrow to the GP and find out.”

Risk-stratification on the basis of lifestyle factors would not be as safe or as easy, she said. A genetic test is a one-off, but lifestyles change and periodic reassessment might be necessary.

Her team has been working on risk-assessment in screening for some years. A paper they published in 2011 was the first to show that it could be beneficial. Real world trials in women eligible for breast screening are now taking place in both Europe and the US.

Routine genetic testing is expected to begin in the NHS this autumn. From 1 October, hospitals will be connected to specialist centres that can interpret the DNA tests given to patients. That will enable drug treatments to be tailored more precisely to a cancer but it is recognised that there could also be a benefit in screening for diseases.

“But first of all the screening programme has to do more good than harm,” said Pashayan, which is what her study suggests. “And then it [genetic testing] must be accessible to all.”

Much would need to be agreed. “Who is going to give the information to women and explain what their risk is? If you are low risk, it doesn’t mean you are not going to get breast cancer and if you are high risk it doesn’t mean that you are. We need to do the preparatory work.”

Another question that her team are now looking into is whether more frequent screening is needed for high risk women. Some women will develop a fast-growing cancer in the interval between three-yearly mammograms.

The study, funded by Cancer Research UK, modelled three groups of women aged 50, looking at what would happen to a group of 364,500 women – the population of women at the age of 50 in 2009 – who were not screened, a second group who had regular mammograms every three years from the age of 50 to 69 as now, and a third group in which low-risk women were not screened but high-risk women were.

In the risk-stratified group, among those who were not screened, there were 27% fewer over-diagnoses, 3% fewer breast cancer deaths avoided, and the NHS cost was reduced by £20,000. In the high risk 70%, there were 71% fewer over-diagnoses, 10% fewer breast cancer deaths avoided, and the NHS cost was £538,000 less.

Prof Fiona Gilbert, a co-author of the study from the University of Cambridge, said: “We need to change the model of delivery of breast screening and recognise that women are individuals with different risks and lifestyles. They should be offered screening tailored to their own profile.

“Over diagnosis is the detection by screening of tumours that would not have been diagnosed in a woman’s lifetime if she had not had screening.”