What good does screening do?

LAST WEEK’S publication of research suggesting that screening for breast cancer has not contributed to the fall in the number of deaths from the disease in the Republic or in Northern Ireland will have surprised many.

Breastcheck, the national breast cancer screening programme, has achieved countrywide coverage in recent years and has a good uptake among its target group. It screened 121,160 women in 2009 when 845 breast cancers were detected, giving a rate of seven cancers per 1,000 women screened.

So does this latest research mean the programme is a waste of time and money?

Let's look at what the British Medical Journalactually found. From 1989 to 2006, deaths from breast cancer decreased by 29 per cent in Northern Ireland and by 26 per cent in the Republic of Ireland.

That’s good news on the face of it, except that comprehensive screening began in the North in the early 1990s whereas the Republic built up its programme gradually, achieving national coverage in 2009.

According to the authors, the results of the analysis suggest that, although a full screening programme had been running in the North for 15 years longer than in the Republic, deaths from breast cancer declined at a similar rate in both jurisdictions.

They compared trends in breast cancer mortality within three pairs of European countries: Northern Ireland versus the Republic; the Netherlands versus Belgium and Flanders; and Sweden versus Norway.

Countries of each pair had similar healthcare services and level of risk factors for breast cancer mortality, but were different in that screening using mammograms was implemented about 10 to 15 years later in the second country of each pair.

The researchers expected that a reduction in mortality would appear sooner in countries with earlier implementation of screening.

In Belgium, Norway, and the Republic of Ireland, however, mortality started to decrease years before most women in the target age groups attended screening.

So if screening hasn’t contributed to the falling number of deaths from breast cancer here, what has? It’s unlikely to be attributable to any change in the biological behaviour of breast cancer. But there have been significant improvements in the organisation of cancer care here.

At one time, surgeons decided which women had any treatment other than surgery – a decision based on the patchy availability of radiotherapy and other interventions.

Now, however, we have a cancer control system where patient management is decided by a multidisciplinary team. The cancer control strategy was introduced after 2006, but the main cancer centres already had revamped their modus operandi some years earlier, and contributed to the mortality improvement.

We must not underestimate the role of radiotherapy. There is evidence of a greater mortality in women who do not receive radiotherapy after breast-conserving surgery.

Nor can the role of adjuvant therapy – the use of chemotherapy and hormone therapy – go unrecognised. A 30-year follow-up of adjuvant chemotherapy with cyclophosphamide, methotrexate, and 5-fluorouracil found that relatively short-term adjuvant treatment for breast cancer is associated with improved survival.

But perhaps the greatest unsung “hero” is the drug Tamoxifen. The first of a class of drugs called aromatase inhibitors – which can help block the growth of tumors by lowering the amount of oestrogen in the body – it and other drugs in its class are given to women with certain types of breast cancer. Taken for years after initial treatment, they have been hugely effective in preventing a recurrence of cancer.

The latest study looks at changing mortality over 18 years but, like all research, it can be challenged. And it is just one piece of research; others have found a 20 per cent lower breast cancer mortality rate in the North compared with the Republic.

In a climate of scarce health resources, this paper cannot be ignored. It raises interesting questions about the role of screening relative to other methods of reducing deaths from breast cancer.

It would need a full health technology assessment by the Health Information and Quality Authority to definitively establish its cost-effectiveness.

This was done before the go-ahead was given for a national colorectal cancer screening programme, but it would be a politically brave move to order an assessment for Breastcheck now it is an established part of our cancer services.

There can be no doubt that the setting up of Breastcheck helped drive a significant improvement in the quality of service for the many women who have discoverd a lump in their breasts and have required urgent treatment for a suspected tumour.