The NHS Just Made Bowel Cancer Screening More Sensitive - Here's What It Means for You

In January 2026, NHS England announced a significant change to its bowel cancer screening programme. The threshold for the Faecal Immunochemical Test (FIT), the home stool test sent to adults as part of routine screening, has been lowered from 120 micrograms of haemoglobin per gram of faeces (µg Hb/g) to 80 µg Hb/g [NHS England, 2026].

This is a meaningful shift. Modelling by the UK National Screening Committee estimated that the lower threshold would detect approximately 663 additional bowel cancers and over 2,000 more high-risk polyps each year, ultimately preventing an estimated 867 bowel cancer deaths annually after 25 years of screening at the new level [UK NSC, 2026]. The change brings England into line with Scotland and Wales, which already use the 80 µg Hb/g threshold.

Why Does the Threshold Matter?

The FIT works by detecting tiny amounts of blood in your stool that aren't visible to the naked eye. The threshold determines how much blood needs to be present before the test flags a positive result and triggers a referral for further investigation, usually a colonoscopy.

At the previous 120 µg Hb/g threshold, the test was already effective at catching many cancers. But a proportion of early-stage cancers and pre-cancerous polyps were being missed because the blood they shed fell below that cutoff. Lowering the threshold to 80 µg Hb/g increases the sensitivity of the test, meaning it will pick up more cases at an earlier, more treatable stage.

The trade-off is specificity. A lower threshold means more positive results overall, including some that turn out not to be cancer after investigation. This increases the demand on colonoscopy services, which is why the change is being rolled out in phases to ensure the NHS has the endoscopy capacity to handle the additional referrals. Full national coverage is expected by March 2028.

It's worth understanding why the threshold exists at all. The NHS screening programme is designed to work at a population level, balancing the number of cancers detected against the available resources for investigation. The threshold isn't a measure of individual risk. It's a tool for triaging a population of millions into those who need further investigation and those who don't, given finite endoscopy capacity.

Why Early Detection Matters

Bowel cancer is the UK's fourth most common cancer and the second leading cause of cancer death, accounting for approximately 16,800 deaths per year [Cancer Research UK, 2024]. But the prognosis is heavily stage-dependent.

According to Cancer Research UK, when bowel cancer is diagnosed at stage 1, the five-year survival rate exceeds 90%. At stage 4, it drops to around 10% [Cancer Research UK, 2024]. That gap is the entire argument for screening. Finding cancers and pre-cancerous polyps before they progress to advanced disease saves lives.

Rising Incidence in Younger Adults

While the NHS screening programme currently targets adults aged 56 to 74 (expanding down to 50 by 2025), there is growing concern about bowel cancer rates in younger people.

A major 2024 analysis published in The Lancet Oncology, using World Health Organisation data from 50 countries, found that early-onset colorectal cancer (diagnosed before age 50) is rising in 27 of those countries [Sung et al., 2024]. England experienced the fourth fastest annual increase at 3.6% per year in the decade to 2017, faster than any other European country.

Cancer Research UK estimates that around 1 in 20 bowel cancer cases in the UK now occur in people under 50. The causes are still being investigated, but researchers point to birth cohort effects: people born after the 1960s have been exposed to higher rates of ultra-processed food consumption, sedentary lifestyles, rising obesity, and changes to the gut microbiome.

If you're under the NHS screening age but have symptoms or risk factors, waiting for a screening invitation is not the right approach. See your GP.

Screening vs Symptomatic Testing: A Critical Distinction

This is one of the most important things to understand about the FIT. The 80 µg Hb/g threshold is for asymptomatic population screening. It is not the threshold your GP uses.

If you go to your GP with symptoms, such as a persistent change in bowel habit, rectal bleeding, unexplained weight loss, or abdominal pain, the NICE guideline NG12 recommends a much lower FIT threshold of 10 µg Hb/g [NICE NG12, 2023]. That's eight times more sensitive than the screening threshold.

A negative screening result does not guarantee the absence of bowel cancer. It means that blood was not detected above the threshold on that particular sample. If you develop symptoms after a negative screening result, you should see your GP regardless.

When to See Your GP

Do not rely on a screening test if you have active symptoms. See your GP promptly if you experience:

• A persistent change in bowel habit lasting three weeks or more (particularly looser or more frequent stools)

• Blood in your stools or rectal bleeding

• Unexplained weight loss

• Persistent abdominal pain, bloating, or discomfort

• A new feeling that you haven't fully emptied your bowel after going to the toilet

You should also discuss screening with your GP if you have a strong family history of bowel cancer (a first-degree relative diagnosed before age 55), a personal history of inflammatory bowel disease (Crohn's disease or ulcerative colitis, which are distinct from the more common irritable bowel syndrome), or a known genetic predisposition such as Lynch syndrome.

In these cases, your GP can arrange surveillance colonoscopies through the NHS at intervals appropriate to your level of risk. A home screening test is not a substitute for this clinical pathway.

How Brooksby Medical Can Help

If you're between NHS screening intervals, under the current screening age, or simply want a quantitative result that gives you an exact number rather than a simple positive or negative, the Brooksby Medical Quantitative FIT Home Test provides a laboratory-grade faecal immunochemical test for £59.

The key difference with the Brooksby test is that you receive a precise numerical result (for example, 5 µg Hb/g or 42 µg Hb/g), interpreted in a GP-written report that explains what your number means and whether further investigation is warranted. This is distinct from the NHS screening test, which reports results as either above or below the threshold.

For a broader understanding of qFIT testing, including how the test works, what affects accuracy, and the evidence behind the different thresholds, our detailed briefing on the qFIT test covers everything you need to know.

References

1. NHS England. Thousands more bowel cancers and high-risk polyps to be caught following screening threshold change. January 2026. NHS England announcement

2. UK National Screening Committee. Recommendation to lower the FIT threshold for the NHS Bowel Cancer Screening Programme. January 2026. UK NSC recommendation

3. Sung H, Siegel RL, Rosenberg PS, et al. Colorectal cancer incidence trends in younger versus older adults: an analysis of population-based cancer registry data. Lancet Oncol. 2024;25(12):1550-1560. doi:10.1016/S1470-2045(24)00600-4

4. Cancer Research UK. Bowel cancer statistics. 2024. CRUK bowel cancer statistics

5. NICE. Suspected cancer: recognition and referral (NG12). Updated 2023. NICE NG12

Written by Dr James Coleman, GP and founder of Brooksby Medical. Dr Coleman is a practising General Practitioner who founded Brooksby Medical to give patients direct access to the blood tests and clinical interpretation they need, without waiting lists.

Medically reviewed: March 2026 | Next review due: March 2027

Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. A negative screening result does not guarantee the absence of bowel cancer. If you have symptoms, please consult your GP regardless of any screening result. Blood test and screening results should always be interpreted by a qualified healthcare professional.