Confusion over cervical cancer screening needs to be resolved once and for all

No screening programme in world detects all cancer precursors

When no abnormality has been found perhaps we could word the report as an assessment of the risk of developing or having cancer rather than that the test is negative. In this way a woman would not perceive total protection. She would not receive false assurance of no risk.  Photograph: Rafe Swan/Getty Images

When no abnormality has been found perhaps we could word the report as an assessment of the risk of developing or having cancer rather than that the test is negative. In this way a woman would not perceive total protection. She would not receive false assurance of no risk. Photograph: Rafe Swan/Getty Images

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I’ve watched the screening programme in Ireland from abroad for the last few years and have been saddened by much of what has happened. Ireland, along with many other developed countries, has a low rate of cervical cancer because of a properly implemented screening programme which detects and treats precancerous conditions.

It was not always so. Ireland used to have a relatively high rate of invasive cervical cancer. Since the introduction of the national screening programme in 2008 the rate has fallen by nearly 7 per cent, year-on-year.

It has been a very successful programme in its primary ambition, to reduce the number of cases and deaths and from cervical cancer. The longer a cervical screening programme continues even lower incidence and death rates will ensue.

Last month the World Health Organisation launched a cervical cancer elimination initiative. It’s long overdue. Cervical cancer is a nasty disease and yet is one of the few truly preventable cancers.

Along with the urgent need to implement global vaccination against the cancer-causing types of human papilloma viruses it is clear that screening programmes are vital to eliminating this preventable cancer, a scourge for women in the prime of their life.

The problem is truly global, although the great majority of cases and deaths are in low or middle-income countries (LMIC) where the tragedy of a maternal death is even more profound, for every 100 women who die from breast or cervical cancer in LMICs 25 children will die, simply because of the added deprivation that they subsequently suffer in losing their mother.

Yet while properly implemented screening programmes that achieve high coverage are successful and cost effective, they are complex, and imperfect. No screening programme in the world detects all cervical cancer precursors.

As Ireland has discovered, false negatives do occur. This is a real tragedy for each and every woman who subsequently develops cancer. But it is not a negligence.

False negative reports

Using current technology false negative reports will continue to happen here, and in every other country’s cervical screening programme, without necessarily there being anyone to blame. This doesn’t negate the need to tackle a case of negligence or other malpractice if and when it occurs.

As Ireland has also discovered, auditing this phenomenon (of false negative reports) is fraught with ethical and legal issues that most countries have not and will not address.

The recently published expert reference group report on clinical audit of interval cancers in the cervical check screened population chaired by Dr Susan O’Reilly confirmed that very few countries undertake previous smear history audit in women with cancer.

Of these, very few encourage or allow access of their findings to the individual patients. Unusually the Irish screening programme both audited and made its findings available. There is no doubt that in so doing mistakes were made, as Dr Gabriel Scally’s report detailed.

As the chief executive of the national screening service, Fiona Murphy, has rightly pointed out unless we deal with the issue of compensation for “false negatives” then the entire screening programme may buckle under the weight of legal costs.

Given the genuine success of the cervical screening service this would be awful, akin to throwing out the baby with the bathwater. It need not happen.

The medical profession, more particularly, those involved in screening services, may have shot themselves in the foot by describing results in a dichotomous way. A diagnosis of pregnancy, cancer or a fractured bone can indeed be a yes or no. Not so with screening tests for cervical precancer. They simply aren’t good enough.

To a doctor, familiar with screening parlance, when a smear test result is reported as “negative” it means that no abnormality has been found, not that no abnormality was present, or would arise over the coming years. Not surprisingly to many people it equates with a mistake. This fundamental difference in interpretation needs to be resolved.

As our understanding of cervical cancer genesis continues to improve so our tests are becoming more accurate (eg HPV genotyping) simpler, less expensive, quicker and, perhaps soon, laboratory independent (eg artificial intelligence image recognition systems). But no matter which tests appear to perform best they should be reported honestly.

Neither an HPV test nor a cervical smear will completely or always recognise, or rule out, normality or precancer then or in the future. Again, this is not negligence. Rather the test will qualify the risk for that person.

Screening tests

For example, the chance of developing cervical cancer is dramatically reduced if the two screening tests (HPV and cervical smear) do not report an abnormality. They do not remove the risk entirely. They are not truly and absolutely negative.

When no abnormality has been found perhaps we could word the report as an assessment of the risk of developing or having cancer rather than that the test is negative. In this way a woman would not perceive total protection. She would not receive false assurance of no risk. There are doubtless other and better initiatives we should consider. This is just one.

Perhaps it’s time for a forum of involved or interested parties, those closest to and affected by the cervical-screening programme, which includes women, nurses and doctors from colposcopy clinics, pathologists, laboratory screeners, epidemiologists, general practitioners, the screening programme, politicians and members of the legal profession.

To my knowledge this broad forum has not yet been convened for this issue which truly needs input from all parties.

We need to make decisions that will resolve the contradictions in our current approach. If we lose the cervical screening programme the death rate from cervical cancer will go up in Ireland, more women will suffer and die than do now from this tragic preventable disease. Walter Prendiville is senior visiting scientist at the International Agency for Research on Cancer and retired associate professor and consultant gynaecologist and director of colposcopy Tallaght and Coombe hospitals

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