Are differences in treatment leading to variation in ovarian cancer survival internationally? – Cancer Research UK


Ovarian cancer is an aggressive disease. In the United Kingdom, ovarian cancer is the 6th most common cancer in women and causes the most deaths of all gynecological cancers.

But researchers are eager to do better not only by developing new treatments and tools to diagnose cancer earlier, but also by understanding whether improvements can be made in the way people are diagnosed and treated in different health care systems.

This is where the International Cancer Benchmarking Partnership (ICBP) – which brings together clinicians, researchers, data experts and policymakers from around the world – enters.

They looked at how ovarian cancer diagnosis and survival differ between countries, hoping to find ways to improve. It’s a project that has become even more important in recent months, according to John Butler, a consultant specializing in gynecological cancer surgery.

“In light of the COVID-19 pandemic and the serious challenges it poses, it is now more important than ever to benchmark efforts and learn lessons from best practices from other countries,” said Butler.

Comparisons like this can be tricky – especially as countries collect and record data in slightly different ways, something the ICBP looks at in more detail. But despite the challenges, the latest ICBP figures are the best available and will only get better as more analysis is done.

And the latest data, which compared ovarian cancer diagnosis and survival in 7 high-income countries, including the UK, reveal that although more people are surviving their cancer, there is still a long way to go.

Variations in Survival

The greatest variations were found in survival rates of older women.

In Norway, for example, more than half of women aged 65-74 survived their disease for 3 years after diagnosis. While in Ireland only about a quarter of women survived for three years. In the UK, only 33% of women in this age group survived for 3 years after being diagnosed.

And the big question was: why are the differences there?

It’s probably complex, because many things can affect how likely a person is to survive their cancer. But one thing that’s less likely to cause differences is how and when people are diagnosed, because there’s room for improvement across the board.

In all 7 countries, the majority of women were diagnosed with advanced or late stage ovarian cancer, ranging from 64% to 71% of women in different countries.

Unfortunately, it comes as no surprise to Butler that more women have advanced disease at diagnosis. “The disease usually starts in the fallopian tubes or the surface of the ovaries and spreads very quickly to the abdomen, so there is less time compared to other cancers between being an early-stage disease and more advanced .” And because the symptoms are usually nonspecific — bloating, abdominal pain, and needing to urinate more often — it can go unnoticed for some time.

It is an area that researchers are eager to improve. “Researchers are doing their best to try to understand how and why we can diagnose and detect ovarian cancer earlier, but this is a highly evolving and complex picture,” Butler told us.

Now that there is a need for improvement across the board in ovarian cancer diagnosis, something else must be driving the variation.

Differences in the treatment of ovarian cancer

The team delved into how ovarian cancer is treated — where differences in surgeries for ovarian cancer became apparent.

In countries with a higher survival rate, such as Norway and Australia, surgeons were more likely to operate before chemotherapy and used more elaborate/radical procedures.

These countries also reported fewer barriers – such as a lack of intensive care capacity or insufficient hospital staff – to provide care than countries like Ireland, New Zealand and the UK, all of which have lower survival rates.

While these variations aren’t necessarily responsible for all of the differences in survival, Butler thinks these barriers are worth investigating.

Since most women with ovarian cancer are diagnosed with advanced disease and are typically older, they are more likely to require complex surgery. This means they will likely need to stay in the intensive care unit if they recover from surgery. “If there is a limitation in access to intensive care, there will therefore be a limitation in the number of patients who receive optimal surgery,” Butler says.

This has become even more relevant when looking at the backlog of services generated by COVID-19.

After reviewing clinical guidelines, the team also found that some targeted therapies were not recommended in two countries: New Zealand and Wales. Targeted therapies have been shown to benefit a small number of patients, such as those with inherited genes, but it is still not clear whether differences in their availability can explain survival differences between countries.

Disclaimer: since the completion of this study, the targeted therapy bevacizumab has now been funded in Wales.

How can we close the gap?

The relationship between cancer treatment and cancer outcomes is complicated, but this research may help shed light on areas for researchers to explore in the future.

What becomes clear from this study is that there are international differences in the treatment of ovarian cancer. And we now need to dig deeper to better understand how these treatment differences might drive the differences in survival across countries.

“The best way to improve service is to measure what happens in the field and learn from it,” Butler explained to us.

Collecting data through audits is a good start. This way we can see whether guidelines and standards for care are being followed and where improvements are needed. For example, audits exist for various cancers, including colon, esophageal, stomach, and head and neck cancers. The same is not true for ovarian cancer, despite the benefits.

Ovarian cancer treatments have come a long way, including more extensive surgeries and more effective cancer drugs. But there is still room for improvement by prioritizing the resources and capacity needed to manage more patients in a strained health system.

And it’s not just treatment — finding ways to diagnose ovarian cancer earlier is a vital part of the equation. And while research into new tests has been challenging, progress is being made. Combining new and innovative tests with greater awareness of ovarian cancer symptoms is the way forward for Butler, which has become even more important than ever in the wake of COVID-19.

“Early diagnosis of cancer is as essential as ever, even in the times of COVID-19, so I would really encourage people to tell their GP if they notice anything abnormal or have signs and symptoms that they are concerned about” Butler says.

Charles Norell is a senior officer and Charlotte Lynch is a research officer on the ICBP team at Cancer Research UK

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