FIT for Follow-Up research summary

Overview

The FIT for Follow-Up study aimed to establish if Faecal Immunochemical Tests (FIT) were a safe, acceptable and cost-effective method of surveillance for post-polypectomy patients who are at increased risk of developing colorectal cancer.

The trial is registered with the ISRCTN registry. Its unique number is 18040196.

Background

Adenomatous polyps have the potential to develop into colorectal cancer and so are commonly removed when found. However, following removal, around 50% of people remain at increased risk of developing colorectal cancer. This risk varies with the number and characteristics of the removed polyps. At the time this study was designed, the 2002 UK guideline for colonoscopy surveillance after polypectomy recommended that patients were divided into low, intermediate and high-risk groups.

According to these guidelines, intermediate-risk patients should have a surveillance colonoscopy three years after polypectomy. However, there are several problems in the use of colonoscopy for this purpose. It is not 100% sensitive, it is a very expensive procedure, and all colonoscopies carry a small risk of serious complications. Colonoscopy is also used to investigate people with colonic symptoms or positive faecal occult blood tests (FOBT) and the number of colonoscopies required was overwhelming the NHS.

At the time of the study, the Faecal Immunochemical Test (FIT) had recently been developed but there was little evidence for its use in colorectal cancer screening. It had several benefits over the previously used guaiac FOBT, including non-reactivity to dietary haemoglobin and modifiable positivity thresholds. We posited that a yearly FIT may be a safe and effective alternative to a 3-yearly colonoscopy for patients with intermediate-risk adenomatous polyps.

Method

Around 8,000 people were invited to take part in the study via the NHS Bowel Cancer Screening Programme. Invited participants were 60-year olds who were deemed to be at intermediate-risk post-polypectomy and were awaiting their 3-yearly surveillance colonoscopy. Around 6,000 people consented to the study. Recruitment began in February 2012 and was completed by December 2013.

While waiting for their first surveillance colonoscopy, eligible participants were asked to complete three annual FITs before undergoing their surveillance colonoscopy. If the result of the FIT in year 1 or year 2 was positive, their surveillance colonoscopy was brought forward, and they did not receive another FIT; otherwise, they had their FIT, as well as their colonoscopy as per usual care, at three years post-polypectomy. Findings at surveillance colonoscopy were used as gold standard against which the programme sensitivity and specificity of the FIT was measured.

Study participants were also asked to complete a questionnaire that included questions focusing on the acceptability of FIT.

Data on participants was collected until 2016 and we received a further set of cancer diagnosis data from Public Health England in 2017.

Results and impact

Our results suggested that FIT could have a place in post-polypectomy surveillance of intermediate-risk patients, especially at a more sensitive detection threshold. The three-year programme sensitivity for colorectal cancer was 59% at a detection threshold of 40μg/g. This increased to 72% at a threshold of 10μg/g. ²

The three-year programme sensitivity for advanced adenomas (adenomas ≥10mm, with villous or tubulovillous histology, or high-grade dysplasia) was 33% at 40μg/g and increased to 57% at 10μg/g. As it takes much longer for adenomas to develop into cancer, this may be an acceptable sensitivity.

We found that FIT was well accepted amongst patients with 97% of consenting patients returning their FITs in years 2 and 3.

The mean incremental cost per participant for three-yearly colonoscopy surveillance versus three years of annual FIT (40μg/g) was £365, and the total cost difference was £2,169,341. Incremental costs per additional advanced adenoma and colorectal cancer detected by colonoscopy surveillance were £7,354 and £180,778, respectively. The national budget impact of replacing colonoscopy with FIT surveillance was -£4.7 million.

If low-threshold annual FIT was implemented instead of three-yearly colonoscopy, the number of colonoscopies could be reduced by more than 70% with significant cost savings. However, this would come at the cost of missed lesions; depending on the threshold, annual FIT could miss 30–40% of colorectal cancers and 40–70% of advanced adenomas.

In our most recent analysis, we investigated sequential faecal haemoglobin concentrations and advanced colorectal neoplasia (ACN) risk in this post-polypectomy surveillance population. The highest rates of ACN detected were observed among those with a positive FIT result in the third year. The lowest ACN detection rate was observed among those whose annual FIT value remained constant across all three years. These results suggest there is potential in using the actual FIT values from multiple rounds of FITs to predict ACN risk.

The main findings from the FIT for Follow-Up study were published in the journal Gut and in the NIHR-HTA Journals Library. Our latest findings in 2025 were published in BMJ Open Gastroenterology.

1. Prevalence of Adenomas and Colorectal Cancer in Average Risk Individuals: A Systematic Review and Meta-analysis. Heitman, Steven J. et al. Clinical Gastroenterology and Hepatology, Volume 7, Issue 12, 1272 - 1278.

2. Computed tomographic colonography versus colonoscopy for investigation of patients with symptoms suggestive of colorectal cancer (SIGGAR): a multicentre randomised trial. Atkin, Wendy et al. The Lancet, Volume 381, Issue 9873, 1194 - 1202.