Improvements recommended for NHS screening programmes that use laboratory tests for bowel cancer, cervical cancer and Down’s syndrome

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1 February 2016

The UK National Screening Committee (UK NSC) is an independent body hosted by Public Health England. It advises ministers and the NHS in the four UK countries about all aspects of screening, and supports the implementation of screening programmes. It published a total of 11 recommendations on 15 January 2016 including improvements to three of the screening programmes that involve lab tests: those for bowel cancer, cervical cancer and Down’s syndrome.

UK NSC recommended that for bowel cancer a faecal immunochemical test (FIT) for human blood should replace the widely used guaiac faecal occult blood test. Last year Scotland committed to adopting FIT, which is also recommended in the European guideline for colorectal cancer screening. FIT is easier to use, requires only a single faecal sample instead of three, has fewer false positives, is more acceptable to users and markedly increases participation rates. The increased sensitivity of  FIT allows the earlier detection of more cancers and pre-cancerous tumours. Deborah Alsina, Chief Executive of the charity Bowel Cancer UK, has pointed out that the increased cancer detection rate will need investment to increase the capacity of follow-up colonoscopy services.

Since 2008 the NHS Cervical Screening Programme has been based on microscope examination for pre-cancerous changes in cells brushed from the cervix into a liquid preservative (liquid based cytology). Abnormal cells are then tested for high risk human papilloma virus (HPV) types. If positive, examination of the cervix for further testing and, if necessary, treatment is offered. We reported in a news item on 2 December 2013 that an international working group had compared that process with an alternative strategy: screening cells for HPV first and then carrying out cytology if the cells were HPV positive. The alternative strategy led to the detection of a larger number of treatable pre-cancerous lesions, and there were fewer missed cancers up to six and a half years after negative HPV tests than after negative cytology. Following further evaluation, UK NSC has recommended adoption of the alternative strategy.

In a news item on 23 April 2015 we reported the results of a large international evaluation of non-invasive prenatal testing (NIPT) of mother’s blood in early pregnancy to diagnose Down’s syndrome. It was shown to be more accurate than the first trimester combined screen and had a much lower false positive rate. Mother’s with a positive screen are offered an invasive test, either amniocentesis or chorionic villus sampling, to make a firm diagnosis. Such tests carry about a 1% risk of miscarriage and a small risk of infection. The UK NSC considered that the evidence suggested that offering NIPT to those with positive screens would detect false positives and so reduce the number of potential miscarriages. They have recommended that NIPT should be implemented with ongoing monitoring and evaluation, so that the programme can be altered if necessary as it is rolled out.