In the UK, we have national cancer screening programmes for cervical, bowel and breast cancer, with targeted lung cancer screening now being rolled out in some regions. But deciding whether to offer screening programmes to the public is far from simple.

While cancer screening can save lives, it can also cause harm.

Potential risks include: false negatives (missing a cancer), false positives (indicating a cancer when there isn’t one), and overdiagnosis (finding a cancer that would never cause harm).

To weigh up the risks and benefits, the UK has an independent, expert, advisory panel called the UK National Screening Committee (UK NSC). This committee has the complex and sometimes controversial task of carefully considering the evidence and advising the Government about whether a screening programme should be adopted or not. The UK NSC’s role is crucial for ensuring cancer screening programmes in the UK are only introduced when the benefits to the public clearly outweigh the harms. 

Let’s look at how it all works.

What are screening programmes?

Screening programmes are designed to spot early signs of disease, like cancer, in people who don’t have symptoms. They aim to improve public health by finding conditions early, when they’re easier to treat. Screening can even help prevent disease, by detecting early changes in the body that could lead to cancer, giving healthcare professionals a chance to step in.

Not every screening programme will benefit everyone. That’s why they usually only invite the people who are most likely to benefit to take part. For example, lung cancer screening is only for people who are at a higher risk of lung cancer, such as people who smoke or used to smoke.

While a safe and accurate test is essential for screening to work, that’s just one part of the picture. Programmes must also consider who is invited, when and how often, how people will be screened and what follow-on treatment and care may be needed. And because screening programmes are expensive, delivering them in a cost-effective way is also important.

Isn’t more screening a good thing?

You might think that screening as many people as possible, for as many health conditions as possible, is a good idea. But screening isn’t risk free.

For each individual, the potential for harm may seem small. But when you consider the many thousands of people that are invited to screening, those risks can add up.

To truly understand the potential risks and benefits, we need high-quality evidence from large screening trials. History has shown what can go wrong when cancer screening programmes are introduced without proper evaluation and evidence.

For example, in the 1990s, Canada introduced screening for neuroblastoma, a rare childhood cancer, for one-year olds. While the program detected more cases, it didn’t reduce the number of deaths from the disease. Instead, many children were overdiagnosed and received treatment that wasn’t needed.* The neuroblastoma screening programmes in Canada, Japan, the USA and Germany were withdrawn following these results.

In the UK, the NSC plays a vital role in reducing the risk of this kind of harm.

How does the government make decisions on screening?

The UK NSC advises the NHS and ministers in all four UK nations on whether to introduce, change, or stop screening programmes – and has done so for more than 100 conditions. The committee is made up of members offering a wide range of expertise, including oncologists, geneticists and patient and public representatives. They’re currently chaired by oncologist and former ‘cancer tsar’ Sir Mike Richards.

To make robust decisions, the UK NSC undertakes an evidence review process. They consider new developments in research, policy and technology and assess evidence** against a strict set of criteria. These criteria help evaluate the effectiveness, feasibility and appropriateness of potential screening programmes. The committee reviews information about the disease in question, the potential screening test, treatment options, the benefits of the screening programme and how it would be implemented. They also consider the quantity, quality, applicability and consistency of the available evidence, and speak to scientists, doctors, charities and the public to ensure a broad range of views are considered.

Based on this review, the UK NSC will release a draft recommendation and invite stakeholders to consider and provide feedback. Only after this consultation process will the UK NSC publish a final recommendation for the Government to consider.

Striking the right balance

Cancer screening can save lives, but it’s not without risks. At Cancer Research UK, we’re committed to improving outcomes for cancer patients, and screening can play a crucial role in that when it’s guided by robust evidence and careful consideration.