Published online Aug 21, 2021. doi: 10.3748/wjg.v27.i31.5272
Peer-review started: February 12, 2021
First decision: April 18, 2021
Revised: May 3, 2021
Accepted: July 20, 2021
Article in press: July 20, 2021
Published online: August 21, 2021
The rate of positive tests using fecal immunochemical test (FIT) does not decrease with subsequent campaigns, but the positive predictive value of advanced neoplasia significantly decreases in subsequent campaign after a first negative test. A relationship between the fecal hemoglobin concentration (Fhb) and the opportunity to detect a colorectal cancer in subsequent campaign has been shown.
In this period of implementation of the optimization strategies of the French program, our motivation was to alert the health authority on the severity of the lesions not diagnosed because of the high positivity threshold of the current screening FIT.
Our objective was to predict the severity of colorectal lesions based on Fhb measured during previous colorectal cancer screening campaign.
The etiological study included 293750 patients aged 50-74, living in Auvergne-Rhône-Alpes (France). These patients completed at least two FIT [test(-1) and test(0)] between June 2015 and December 2019. Delay between test(-1) and test(0) was > 1 year, and test(-1) result was negative (< 150 ngHb/mL). The severity of colorectal lesions diagnosed at test(0) was described according to Fhb measured at test(-1) [Fhb(-1)]. The relationship between the severity classified in seven ordinal categories and the predictive factors was analyzed in an ordered multivariate polytomous regression model.
The test(0) positive rate was 4.0% and the colonoscopy completion rate was 97.1% in 11594 patients who showed a positive test(0). The colonoscopy detection rate was 77.7% in those 11254 patients who underwent a colonoscopy. In total, 8748 colorectal lesions were detected (including 2182 low-risk-polyps, 2400 high-risk-polyp and 502 colorectal cancer). The colonoscopy detection rate varied significantly with Fhb(-1) [0 ngHb/mL: 75.6%, (0-50): 77.3%, (50-100): 88.7%, (100-150): 90.3%; P = 0.001). People with a Fhb(-1) within (100-150 ngHb/mL) (P = 0.001) were 2.6 (2.2; 3.0) times more likely to have a high severity level compared to those having a Fhb(-1) value of zero. This severity risk was reduced by 20% in patients aged 55-59 compared to those aged < 55 [adjusted odds ratio: 0.8 (0.6; 1.0)].
The study showed that higher Fhb(-1) is correlated to an increased risk of severity of colorectal lesions. This risk of severity increased among first-time participants (age < 55) and the elderly (≥ 70). To avoid the loss of chance in these age groups, the FIT positivity threshold should be reduced to 100 ngHb/mL. The other alternative would be to reduce the time between the two tests in these age groups from the current 2 years to 1 year.
At the end of this study, we aim to conduct an experiment with a screening program considering the age of patients and the previous values of the fecal hemoglobin concentration.