Colorectal cancer prevalence in faecal immunochemical test non-returners: potential for health inequality in symptomatic referral pathways.

Background: This study aimed to describe the faecal immunochemical test non-return rate of those referred with high-risk symptoms of colorectal cancer from primary care, and the clinical outcomes of the 'non-returners'.

Methods: From January 2019 to July 2021, patients referred to secondary care with symptoms suspicious of colorectal cancer and a referral priority of urgent or urgent suspicion of cancer were sent a faecal immunochemical test. All patients were investigated regardless of faecal immunochemical test return or result. Demographics and clinical outcomes such as colorectal cancer prevalence were compared between those who returned a faecal immunochemical test and non-returners.

Results: Of 7345 patients included in the study, 874 (11.9%) did not return a faecal immunochemical test. Non-returner characteristics included male sex (P = 0.040), younger age (median age 57 versus 65 years, P < 0.001), per rectal bleeding (P < 0.001) and lower socioeconomic status (median Scottish Index of Multiple Deprivation, 6 versus 7, P < 0.001) compared with those who returned a faecal immunochemical test. Of 6294 patients undergoing colorectal investigation, there was a greater prevalence of colorectal cancer (5.4% versus 3.6% P = 0.032) and significant bowel pathology than in the non-returners (15.3% versus 9.8%, P < 0.001). With a median follow-up of 25 months, the colorectal cancer prevalence for the entire 7345 cohort was equal between those who returned and did not return a faecal immunochemical test (3.2% versus 3.8%, P = 0.108). Of note, the non-returners diagnosed with colorectal cancer were younger (median age 64 versus 73 years, P < 0.001) and from a lower socioeconomic area (median Scottish Index of Multiple Deprivation 4 versus 7, P = 0.015) than faecal immunochemical test returners.

Conclusion: Patients referred to secondary care, with symptoms suspicious of colorectal cancer, that did not return a faecal immunochemical test had a similar colorectal cancer prevalence to those that returned the test.