Is it safe to export cancer screening?

A woman in the Republic of Ireland, Vicky Phelan, recently settled with a laboratory in America receiving $2.5million compensation for them missing abnormalities on her cervical screening test. Sadly, Ms Phelan now has advanced cervical cancer.

We don’t know the details of the case, however this news item raises important questions for cancer screening programmes.

In the latter half of the twentieth century cervical screening was performed by taking a swab from the cervix and looking at the cells under a microscope – a process called cytology. Looking at the cells is not easy. The individual needs good training and regular breaks. And since it is subjective, most screening programmes require at least some samples to be looked at independently by a second person. Even with these quality control measures mistakes can happen. Because most women being screened are perfectly healthy, finding abnormal cells that need treating is a bit like finding a needle in a haystack.

Even though screening is not perfect it works extremely well. Fortunately, most cervical cancers develop over many years, so even if an abnormality is missed on one screen, it will probably be picked up on the next screen still in time to prevent it from developing into cancer. This means that the better the screening test the less often one needs to screen. Or put another way, the less good the test the more often you need to use it.

Historically the Republic of Ireland has had lower rates of cervical cancer than many European countries and therefore did not prioritise the introduction of cervical screening. Despite this, some of the leading cervical screening doctors in the world are from Ireland.

It was in the early 2000’s that Ireland decided it should have a cervical screening programme. But it had a problem. Because there had been little screening in Ireland there were not enough people who had been trained to look at cytology tests under the microscope. They had a difficult choice to make. Should they try to train lots of people in cytology and set up a system of laboratory quality control or should they send the samples abroad to be examined.

Photo by Josh Sorenson from Pexels

The Irish screening programme decided to send samples abroad. Unfortunately, they chose a laboratory in the USA. Since women in the USA were screened annually, laboratories in America did not need to worry as much about not missing an occasional abnormality. Laboratories in Nordic countries and the UK where women were screened every 3 to 5 years (depending on your age) put far greater emphasis on quality assurance. Studies showed that labs in the UK picked up about 80% of high-grade lesions (disease that would be treated if found), whereas laboratories in North America only found about 50% of such disease.  Studies from Germany showed that they only found about 20% of disease – which is why in Germany screening is still offered annually.

Tragically, it appears that the standard of cytology in American laboratories was not good enough for use in a screening programme which only offered testing every three years.

Ireland did have another option when it was designing its cervical screening programme. Even then it was clear that HPV testing could be done robustly in a central laboratory and did not require subjective judgement by highly trained individuals. Although it was not clear back then that HPV was better than high-quality cytology, it was clear that HPV testing was extremely good and mass screening using HPV testing could be introduced much more rapidly than mass screening using cytology. However, Ireland decided to try to replicate what all other cervical screening programmes were doing at the time, rather than being innovative and being a first adopter of HPV testing for primary screening. Irish women have paid the price.

The Taoiseach (Irish prime minister), Leo Varadakar has announced that the Republic will introduce primary HPV testing later this year.  Sadly, this announcement comes too late for 208 women who have been diagnosed with cervical cancer following a missed abnormality on screening.

What can we learn from this sorry story?

When it comes to public health, a government cannot safely contract their obligations to look after the health of their population to other countries. It is one thing to consult with international experts or to ask for help during an epidemic or with a patient with a very rare condition. But is it quite another to export screening to another country and thereby loose all control over the quality and performance of the service.

You may be interested in the following updates and related content

Update of Vicky Phelan

Roll-out of HPV primary screening in Wales

Screening sensitivity

The views expressed are those of the author. Posting of the blog does not signify that the Cancer Prevention Group endorse those views or opinions.

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