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UK breast cancer survival is worse than in comparable countries – why?

In the UK we’re making great progress against breast cancer – over 85 per cent of women diagnosed with the disease survive for at least five years. And around two thirds of all women diagnosed with breast cancer can expect to survive their disease for at least 20 years.

But today’s results from the International Cancer Benchmarking Partnership (ICBP) – a study of cancer survival rates in some of the worlds’ richest countries – serve as a reminder that we could be doing even better, and it gives some clues about how.

It’s the latest in a string of important papers from ICBP. The first showed that while UK survival is improving, it lags behind the best in the world. And for the four cancers studied in ICBP, it is only in breast cancer that are we closing the gap.

Two recent papers examined the reasons for the UK’s relatively poor ovarian and lung cancer survival. They suggested that the differences between countries – and the UK’s poorer statistics – were caused more by differences in access to treatment than by being diagnosed at a late stage.

The new research, which drew on data from more than 250,000 breast cancer patients, paints a similar picture. It shows that survival rates for women diagnosed in the UK are lower than those in Australia, Canada, Norway, Denmark or Sweden – with 87 per cent of women survived their disease for at least three years after diagnosis (known as ‘three-year survival’) compared with 94 per cent in Canada (the highest in the study).

Although the overall differences between the countries weren’t that large – women with breast cancer generally fare well across all the countries studied – a closer look at the numbers reveals some good and some bad news.

This is possible because, like the lung and ovarian cancer studies, the new analysis also looked at the proportion of breast cancers diagnosed at different stages of the disease, and tallied this against the chances of surviving at each of these stages. This yields important clues about the root causes of the UK’s poorer breast cancer survival. Let’s have a look at the details.

Late diagnosis probably isn’t the problem

On one hand there was some good news for the UK. The proportion of UK breast cancer patients diagnosed at an early stage (stages 1 and 2), before the disease has spread, was similar to the proportion in Canada, Norway and Sweden (all countries that do better than us in terms of breast cancer survival). So it’s unlikely we have a particular problem with late diagnosis of breast cancer in the UK. Instead, the problem might be down to how we treat certain patients.

But we shouldn’t rest on our laurels over early detection. Although around 85 per cent of women in the UK are diagnosed with an early stage cancer, we still need to continue improving early diagnosis of breast cancer in the UK.

We already know that when breast cancer is found early the chances of surviving breast cancer are considerably improved and the new study just further highlights this. It showed that UK women diagnosed in the early stages (stage 1) had a greater than 99 per cent chance of surviving their disease for three years, while those diagnosed in the late stages (stage 4) had only 28 per cent chance of surviving for three years.

It’s highly likely that all countries in this study could benefit even more from efforts to diagnose more breast cancers in the early stages.

Early stage breast cancer – the UK is as good as the best

And there was more good news. When diagnosed at the earliest stage (stage 1), women in the UK were just as likely as women in Norway or Sweden to survive breast cancer.

In fact, when diagnosed at stage 1, more than 99 per cent of women survived their disease for at least 3 years in all countries included in the study. This suggests all of these countries are good at treating early stage breast cancer.

Late stage breast cancer – the UK lags behind

Unfortunately the same wasn’t true for UK women diagnosed with breast cancer in the more advanced stages. By stage 3 or 4 (when breast cancers had spread to the lymph nodes or to other parts of the body) breast cancer patients in the UK fared considerably worse than those in all other countries studied.

Only 28 per cent of women diagnosed with breast cancer that had spread to the bones, liver, lung or brain (stage 4) survived their disease for at least three years, compared to 42 per cent of Swedish women. At stage 3 the picture is somewhat better, but UK patients still do worse than their counterparts in other countries – with 71 per cent surviving their disease for at least three years while in Canada 82 per cent survive.

If late diagnosis is unlikely to be behind the UK’s relatively poor breast cancer survival, what could be the explanation?

Are the figures comparable?

One possible explanation for the UK’s poorer survival rates at stages 3 and 4 could be that we are comparing apples and oranges. We have, up to now, assumed that stage 3 breast cancer in Sweden is identical to a stage 3 breast cancer in Canada, and that a stage 4 breast cancer is the same whether you are in the UK or Norway. But what if this isn’t the case?

To find out how advanced a breast cancer is, doctors use tests and scans to work out whether it has spread to the lymph nodes or other parts of the body. This is known as ‘staging’. You can find out more about these tests and scans on our website.

If doctors in some countries were more likely to send breast cancer patients for scans and tests, we might expect these countries to be more likely to find evidence that cancers had spread to lymph nodes, bones or liver than a country that did not do the same tests.

Let’s take a hypothetical scenario – let’s say doctors in country A are less likely to send breast cancer patients for bone scans than doctors in country B. So, in country A some patients with breast cancer that has spread to the bones (stage 4) would be diagnosed as having stage 3 disease (spread to the lymph nodes but not the bones) because the bone scans weren’t done.

In country B, where the bone scans were done, the cancer would be diagnosed as stage 4. So a breast cancer classified as stage 4 in country B could be called stage 3 in country A.

If UK doctors are less likely to perform scans (like country A in the example above), then it could explain why stage 3 breast cancers in the UK have poorer survival than Sweden (because some of them are actually stage 4 according to Sweden’s definition, and country B in the example above).

It could also explain why UK stage 4 breast cancers have particularly poor survival (because those stage 4s with the best outlook have been classified as stage 3, leaving only those with the very worst prognosis in the remaining stage 4 category.)

While this is a hypothetical scenario, there may be some truth in it. The authors of the study point out that previous research suggests that UK doctors are indeed less likely to do these staging investigations. Moreover, the authors remark that guidance from the National Institute for Clinical Excellence (NICE) says women without symptoms should not undergo staging investigations such as whole body bone and CT scans for metastatic disease.

So it seems possible that the staging procedures in the UK may be contributing to our poor survival figures for late stage breast cancer. We can’t rule this out and it certainly needs further investigation.

Issues of treatment quality, access to treatment or sicker patients

But there are other possibilities – and we discussed these in depth in previous posts about ICBP.

One is that there’s a problem with how we treat late stage breast cancer in the UK. This, in turn, could be for three reasons. First, our doctors may not be as good – but this seems highly unlikely given the huge progress made in recent years.

Another possibility is that UK doctors don’t have access to the latest, cutting edge treatments. Or it could be that they have access to these treatments, but choose not to use them in late-stage disease. It’s more difficult to say conclusively whether either of these two latter phenomena could be happening in the UK, and it’s clearly an area that needs to be looked into in more detail.

Another potential explanation is that breast cancer patients in the UK may, on average, have more additional health problems than their counterparts in other countries (for example, they may also have heart disease). This could mean they would be less likely to be offered certain treatments, or less likely to tolerate or complete this treatment – and so their chances of survival would be poorer.

Where does that leave us?

This study shows that the UK’s breast cancer survival rates are, overall, worse than in other rich countries with similar healthcare systems. This seems to be being driven by particularly poor survival in the late stages – we’re pretty good at treating early-stage disease, which is great news for the majority of breast cancer patients who are diagnosed with early stage disease.

But saying anything more is hampered by the possibility that, when it comes to cancer stage, we may not be comparing like with like.

What is clear is that even more detailed studies of breast cancer staging procedures, treatment access and the health of UK breast cancer patients would be of immense value to the medical profession, policy makers and, ultimately, to the thousands women diagnosed with breast cancer each year.

While it may seem frustrating that a study this detailed yields more questions than it answers, that – unfortunately – is often the way of science. Understanding the way healthcare systems work – why they succeed and fail, what constitutes ‘best practice’, and how to improve things – is very much a new field of research.

But it’s one that we need to press ahead with, to make sure every cancer patient gets the treatment they deserve.

Reference
Walters S. et al. (2013). Breast cancer survival and stage at diagnosis in Australia, Canada, Denmark, Norway, Sweden and the UK, 2000-2007: a population-based study, British Journal of Cancer, DOI: