Why smear tests matter: cervical screening ‘saves 2,000 lives a year’

    20 September 2016

    Cervical screening prevents 70 per cent of cervical cancer deaths, according to research at Barts and the London School of Medicine and Dentistry.

    In England the disease kills about 800 women a year. The study, published in the British Journal of Cancer, found that if all eligible women regularly attended screening sessions this figure would rise to 83 per cent. This means that an extra 347 lives could be saved every year.

    Cervical cancer screening is offered in the UK to women between the ages of 25 and 64. Women are invited every three years between 25 and 49; after that they are invited every five years until they are 64.

    The researchers studied the records of more than 11,000 cervical cancer patients in England.

    They predicted that over 1,800 more women would die from the disease each year if there was no screening.

    The study’s lead researcher, Professor Peter Sasieni, said: ‘This study looked at the impact of cervical screening on deaths from the disease and estimated the number of lives the screening programme saves each year.

    ‘Thousands of women in the UK are alive and healthy today thanks to cervical screening. The cervical screening programme already prevents thousands of cancers each year and as it continues to improve, by testing all samples for the human papilloma virus, even more women are likely to avoid this disease.’

    Instant analysis
    This paper sought to illustrate the effect of cervical cancer screening on mortality. This is not easy to achieve. Generating certainty from the statistics requires a large number of unscreened women to be included in the sample.

    The study drew data from the Audit of Invasive Cervical Cancers. For each of the 11,000 cases of cancer included, two controls were selected – that is, women selected according to location and age to match a counterpart in the cancer group.

    At all ages, screening was associated with a reduction in cancer diagnoses. Particularly, at age 50-64, screening was associated with a decreased incidence in cancer at 65-79 years. The effect was amplified when it came to more advanced stages of cancer.

    The authors estimated that 2.53 times more cancer would be diagnosed between the ages of 25-79 in the absence of screening; however, if everyone was screened, it would be a third less.

    The area of greatest impact for screening is between the ages of 50-64, where the incidence rate would be over four times higher with no screening, and less than half if everyone was regularly screened.

    The paper compared three categories in terms of five-year mortality rates: no screening, regular screening, and screening as it is currently taken up.

    In the absence of screening, cervical cancer mortality would be four times higher for those between 35 and 49 and five times higher for women between 50 and 64. If everyone was screened, mortality would be less than half what it currently is.

    It is generally accepted that cervical screening reduces cervical cancer incidence, but this study helps to improve understanding of exactly how much.

    The obvious conclusion would be to suggest that everyone eligible should routinely attend for their smear, but people make informed choices and have their own reasons for attending or not. The point I would make is that there is pretty strong evidence that the screening works, and does save lives.

    What I have seen in practice is that, after the HPV vaccination programme, a lot of younger patients believe that smears are not required for them, as they have been vaccinated. This is, of course, not true.
    Research score: 4/5