Introduction
Population-wide screening for cancer – i.e. testing for cancer when no symptoms are apparent enables the disease to be caught at an earlier stage when it is more curable. There are four main cancer screening programmes currently in use in the UK covering cancers of the bowel, breast, lung and cervix.
Overall stewardship of the programmes resides with the Dept. of Health and Social Care, with the UK National Screening Committee (UKNSC) advising the department on introducing and amending screening programmes in all four UK nations who then interpret their advice as they see appropriate.
In general terms, the UKNSC is innovative in its approach, pro-actively looking for potentially efficacious new screening programmes as well as considering the use of stratified and targeted methods for more effective screening of relevant populations.
As a result, there have been considerable advances in UK cancer screening over the years, such as the move from the gFOBT bowel cancer test to the FIT test; the digitalisation of breast screening imagery and the expected use of AI in the reading of such imagery; the introduction of the HPV vaccine against cervical cancer leading to the possibility of the eradication of the cancer (although the cervical screening programme is still relevant); and finally, the introduction of lung cancer screening. This is a testament to the effectiveness of the UKNSC.
However, our key criticism of the screening programme as a whole is that it offers no information in the prevention of these highly preventable cancers; it must be the case that if catching cancer early is beneficial, it is infinitely more beneficial to prevent the cancer in the first place. We recommend that the remit of the UKNSC should cover information and awareness as key weapons in the armoury against cancer.
Bearing in mind that the NHS sends out several million individual notifications for their screening programmes each year, we consider it unfortunate that the UKNSC does not take the opportunity to give people greater information about how they can protect themselves from developing these dread diseases. 54% of current bowel cancer cases are estimated to be preventable[1], 85% of lung cancer cases[2] and 25% of breast cancer cases preventable[3] by modifying diet and lifestyle. Cervical cancer can now largely be prevented by vaccine and may in due course be eradicated.
Our second point of criticism concerns the upper age limit of screening programmes. It is an unfortunate fact that the more likely you are to get one of these cancers, the less likely you are to be screened for them. This is because cancer tends to be a disease of old age, and most cancer screening programmes cease screening after the patient has reached their early 70s. This severely affects the efficacy of screening; for example, bowel cancer screening only catches some 10% of all cases, in spite of the fact that the screening process uses a highly efficacious bowel cancer test.
There are some sensible medical reasons for ceasing screening in the elderly which mainly relate to the side effects of false positives or false negatives and “over diagnosis”. However, the older age limits have mostly not changed since the commencement of these programmes, sometimes as much as twenty or thirty years ago. Surely it is time to review the upper age limits to see whether, given general advances in clinical practice, screening for the elderly would now be a net benefit? The response by the NHS to this issue is that it is possible for an individual to “opt-in” to screening after the upper age limit.
However, no information is given to the individual as to why screening has stopped or on what grounds it is sensible to continue to be screened, and in fact, very few people take up the offer. This contrasts to the efforts that are made at the commencement of screening to inform the patient of the pros and cons of screening. Bearing in mind that the statistics show considerable better outcomes for cancers caught by screening, this is an important issue.
Finally, many perspicacious observers have commented that not only is it more effective to deal with cancer in its early stages but it is also financially cheaper than trying to deliver curative treatment when the cancer has advanced. This is a fact that we believe should be given greater prominence. It also means that the case for investing in additional screening capacity is always likely to be very strong, and so limitations in screening capacity should never be seen as a sound reason for limiting the scope of screening programmes in anything other than the short-term.
We take each screening programme in turn:
Bowel Cancer Screening
Faecal Immunochemical Test (FIT) tests are sent to both men and women aged from 50 to 74 at home every two years. Stool samples are requested for testing. Around 4.4 million people are invited for screening, of whom 2.5 million typically return a sample. There is around a 60% uptake (57.7% in 2017/18). This screening is considered to save about 2500 lives a year[4].
Further investigation is undertaken when a sample has 120 micrograms or above of haemoglobin per gram of stool. Around 2% of patients can be expected to have a positive result. Such patients are followed up with a colonoscopy, of which around 10% will have cancer. Important improvements that have been put in place, or are being considered, include reducing the lower age limit for inclusion in the programme, and making the test more sensitive and thus catching cancers at an earlier stage. Key drawbacks to extending the programme are colonoscopy capacity and pathology capacity restraints.
Prior to Covid, a bowel scope test was experimentally introduced, as a one-off test aimed at people aged 55, known as a flexible sigmoidoscopy. This involves the introduction of a thin flexible tube into the lower end of the bowel to identify any small growths or “polyps” that may turn into cancer with the aim of removing them before they become cancerous. In 2018/19 385,000 people were invited for testing of which 182,000 underwent the test[5]. Interrupted by Covid, it has now been discontinued.
Additionally, there has been increased emphasis on identifying Lynch syndrome, a genetic condition that makes people more susceptible to bowel cancer.
Our View:
Bowel cancer screening is a superb programme. It is non-invasive, easy and effective. Reducing the lower age limit to 50 for the test has now been completed in England and Wales, bringing it in line with Scotland, which we applaud. However, some 45% of bowel cancers occur in the over 74 age group, and bearing in mind that this age limit was brought in at inception of the programme in 2006, it is difficult to see why advancements in colonoscopy have not enabled an older cohort to take part.
Additionally, we believe the NHS should persevere with the bowel scope screening test, which was derailed by Covid. Bearing in mind the high financial costs, let alone the human cost, of treating bowel cancer, we believe that the bowel scope screening project should be reappraised and kept on the agenda.
Finally, of all the cancers being screened, bowel cancer lends itself to prevention through greater awareness and information. There should be more information in the screening notifications sent to people about how people can reduce their risk of bowel cancer. The key modifiable lifestyle and dietary risks are as follows:28% of bowel cancer cases are caused by lack of dietary fibre; 13% from eating too much red and processed meat; and about 25% are caused by smoking, obesity and alcohol.[6] Of all these dietary and lifestyle risks associated with bowel cancer, increasing dietary fibre and reducing intake of red meat are some of the easiest for individuals to effect, yet evidence shows that most people are insufficiently aware of these benefits.
Breast Cancer Screening
This was one of the earliest screening programmes in the UK and was established in 1988. By 2000, it included women aged 50-70 while those over the age of 70 could self-refer. The screening programme consists of a mammogram every three years which is then inspected for signs of developing cancer. Each year about (2017/18) 2.9 million women are invited for breast screening with about 1.8 million attending and 18,000 cancers detected.[7] The screen is estimated to save one life for every 1,200 women screened, or up to 1,700 lives per year. About 18,000 women had cancers detected by the programme, a rate of 8.4 per 1000 women screened. The rate increased for those over 70 to 14.6 per 1000 women screened.[8] Additionally, a total of 6,519 high risk women were screened of all ages who had genetic mutations such as BRCA1 and 2.
In 2010, there was a controlled trial to extend the screening programme, known as the AgeX trial, to increase the age range for screening from 50-70 to 47-79, but it was discontinued during Covid.[9]
The technology of mammograms has improved over the years with digital imaging now being standard. Additionally, AI has been shown to be satisfactory for reading the images, and could well be introduced in the near future enabling screening capacity to be expanded and therefore extended to a wider population of women.
Our View:
Breast cancer screening has a high profile in the battle against breast cancer and generally has high participation levels. However, the effectiveness of screening for breast cancer is not straightforward to measure, and several clinicians have questioned its purpose. This is largely due to the high levels of false positives/negatives, and over-diagnosis that the screening can deliver (although this is an issue with most screening systems).
Nevertheless, all screening systems can be improved over time, and breast cancer screening has shown itself particularly amenable to modern technological advances. Although the use of AI in reading images has not yet been introduced, it is fair to assume that there is considerable potential in this area. We can also assume that the screening programme has made a positive contribution to the considerable improvement in breast cancer outcomes in recent years compared to other cancers, and will continue to do so in the future.
Lung Cancer Screening
In 2022 a targeted lung health check was introduced in the NHS which in 2023 was developed into a lung cancer screening programme. This is now gradually being rolled out through the UK. People aged 55 to 74 with a history of smoking in GPs’ records are invited for an assessment, screening and smoking cessation services. Low dose computerised tomography (CT) is used to screen individuals at higher risk of developing the cancer. The NHS is focusing on reaching 40% of the target population by the end of 2025, with 100% being reached by 2030. Additionally, greater emphasis has been placed on delivering the screening programme to areas of high social deprivation[10]. In Scotland and Northern Ireland there are ongoing lung cancer screening pilots, and in Wales it is expected that a similar screening programme will commence in 2027 if not before.
Our View:
Lung cancer is one of the deadliest cancers as a result of constant late diagnosis. The ‘targeted lung health check’ showed that screening resulted in 76% of those tested having their cancer diagnosed at an earlier stage[11], and thus can be seen as a success. However, we have some concerns that one negative impact of a well-publicised screening programme could be that it gives some smokers a greater sense of security and therefore potentially a psychological “licence to smoke”, bearing in mind that nicotine is a highly addictive substance.
Smoking cessation services are delivered by local authorities who, under significant financial pressures, have often cut back on such services, whilst the screening programme is delivered by the NHS. The NHS need to take measures to maximise smoking cessation support delivered alongside this screening programme to ensure that the programme has a positive impact and is not encouraging people to continue smoking.
Cervical Screening
This programme was established in 1988 and is offered to women aged 25 to 64 either every three years or five years. It consists of 12 tests in a lifetime. It started as a “smear test” and has now transitioned to primary HPV testing. 4.5 million women were invited for screening in 2017/18, with an uptake of 71.5%[12]. Much of the objective of cervical screening has now been overtaken by the use of the HPV vaccine, but screening is still required as the vaccine does not cover all types of the HPV virus. Unfortunately, publicity surrounding the vaccine has led to a steady fall in uptake for screening. However, the introduction of HPV self-sampling has helped to remedy this, especially in harder-to-reach communities.
Our View:
The introduction of an HPV vaccine, which protects against the human papillomavirus virus, puts the potential eradication of cervical cancer on the agenda. This is a highly successful prevention process which we strongly support. The vaccine helps prevent the types of HPV virus that are responsible for most cervical cancers, although as it does not protect against all HPV strains. Therefore, cervical screening is still necessary. As such, the introduction of the HPV vaccine is currently complementary to the screening process; both are crucial for optimal protection. It is also worth noting that the vaccine has the potential to protect against several other cancers such as mouth and neck cancers. The vaccine is most effective when given before exposure to HPV virus, usually during adolescence. In the UK it is offered to girls and boys aged 12-13 in all schools. The NHS intends to eliminate cervical cancer by 2040.[13]
[1] https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/bowel-cancer
[2] https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/lung-cancer
[3] https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer
[4] https://www.england.nhs.uk/wp-content/uploads/2019/02/report-of-the-independent-review-of-adult-screening-programme-in-england.pdf p115
[5] https://www.england.nhs.uk/wp-content/uploads/2019/02/report-of-the-independent-review-of-adult-screening-programme-in-england.pdf p117
[6] https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/bowel-cancer#BowelCS3
[7] https://www.england.nhs.uk/wp-content/uploads/2019/02/report-of-the-independent-review-of-adult-screening-programme-in-england.pdf p119
[8] IBID
[9] https://www.healthsense-uk.org/news/208-agex-ends.html
[10] https://www.england.nhs.uk/blog/rolling-out-targeted-lung-health-checks/
[11] https://www.england.nhs.uk/blog/rolling-out-targeted-lung-health-checks/
[12] https://www.england.nhs.uk/wp-content/uploads/2019/02/report-of-the-independent-review-of-adult-screening-programme-in-england.pdf p122
[13] https://www.england.nhs.uk/2023/11/nhs-sets-ambition-to-eliminate-cervical-cancer-by-2040/#:~:text=Professor%20Peter%20Johnson%2C%20national%20clinic