Finding the needle in the haystack: the diagnostic accuracy of the faecal immunochemical test for colorectal cancer in younger symptomatic patients

Abstract

Aim Detection of early onset colorectal cancer is challenging, and remains a rare diagnosis amongst younger people with gastrointestinal symptoms. We investigated whether faecal immunochemical testing (FIT) could identify younger patients at higher risk of colorectal cancer or serious bowel disease including colorectal cancer, inflammatory bowel disease or advanced adenomas. Methods A subgroup analysis was performed of symptomatic patients under 50 years of age (<50) from the NICE FIT study, a multicentre, prospective diagnostic accuracy study of FIT conducted between October 2017 and December 2019. The diagnostic accuracy of FIT for colorectal cancer and serious bowel disease was investigated in younger patients at different faecal haemoglobin (f‐Hb) cut‐offs of 2, 10 and 150 µg blood/g faeces (µg/g). Results Early onset colorectal cancer was diagnosed in 1.5% (16/1103) of younger symptomatic patients. The sensitivity of FIT for younger patients aged <50 was 87.5% (95% CI 61.7%–98.4%), 81.3% (54.4%–96.0%) and 68.8% (41.3%–89.0%) at f‐Hb cut‐offs of 2, 10 and 150 µg/g, respectively. The positive predictive value for colorectal cancer increased from 4.2% (2.3%–6.9%) to 11.5% (5.9%–19.6%) at cut‐offs of 2 and 150 µg/g, while the positive predictive value for serious bowel disease increased from 31.3% (26.3%–36.5%) to 65.6% (55.2%–75.0%) at the same cut‐offs. The negative predictive value of FIT for colorectal cancer remained above 99.5% at all cut‐offs. Conclusion Detectable f‐Hb on FIT in symptomatic younger patients may indicate referral for investigation of colorectal cancer and serious bowel disease.

Faecal immunochemical testing (FIT) in patients with signs or symptoms of suspected colorectal cancer (CRC): a joint guideline from the Association of Coloproctology of Great Britain and Ireland (ACPGBI) and the British Society of Gastroenterology (BSG)

“…A diagnostic test that can identify those younger patients at risk of cancer may therefore be useful as an adjunct to decide on referral to secondary care for further investigation. The diagnostic accuracy data of FIT in younger patients (<50) was the primary endpoint in one study, 116 but reported in subgroup analyses in three further studies. 13 29 53 Souza et al investigated the diagnostic accuracy of FIT in 9822 symptomatic patients in the UK, and had a particular focus on 1103 symptomatic patients under the age of 50.…”

“…The diagnostic accuracy data of FIT in younger patients (<50) was the primary endpoint in one study,116 but reported in subgroup analyses in three further studies 13 29 53. Souza et al investigated the diagnostic accuracy of FIT in 9822 symptomatic patients in the UK, and had a particular focus on 1103 symptomatic patients under the age of 50 116. The prevalence of CRC was 1.5% (16/1103) in younger symptomatic patients.…”

The use of the faecal immunochemical test during the COVID‐19 pandemic to triage urgent colorectal cancer referrals

“…Despite this, 0.36% is much lower than the 4%-6% of cancers which may be missed when colonoscopy is used as a screening tool [15][16][17]. A recent subgroup analysis of a multicentre trial looking into the use of FIT as a predictive tool for CRC has shown that a positive f-Hb using FIT on symptomatic patients under the age of 50 may indicate the need for referral for investigation of CRC or serious bowel TA B L E 6 Subgroup analysis of the endoscopic findings within the FIT triage cohort based on FIT cut-off levels compared to the total number of patients within the FIT triage cohort [18]. The age group is significantly younger than the median age of the cohort in our study (72 years).…”

Is the quantitative faecal immunochemical test (qFIT) ready for prime time in the US?

“…Data had been limited regarding the diagnostic accuracy of qFIT in symptomatic younger patients with suspected CRC symptoms. A subgroup analysis of the 2021 NICE FIT study focused on younger patients (aged <50) found a moderate sensitivity of 87.5% and 81.3% at lower cutoffs of 2 and 10 μg/g, but the prevalence was 11.5% at the highest cutoff of 150 μg/g [23]. The negative predictive value for CRC remained above 99.5% at all cutoffs, and FIT was associated with a high prevalence of significant bowel disease (46.1%) at the 10 μg/g cutoff recommended by NICE DG30 [24].…”

“…The recent collection of studies on quantitative faecal immunochemical test (qFIT) use in symptomatic patients in Colorectal Disease [7][8][9][10] and its widespread adoption as a screening modality in Europe has compelled reflection on its use in practices for both asymptomatic and symptomatic CRC detection and screening in the US. Other healthcare structures are similarly structured.…”