Published online Nov 15, 2022. doi: 10.4251/wjgo.v14.i11.2195
Peer-review started: July 26, 2022
First decision: August 19, 2022
Revised: September 6, 2022
Accepted: October 2, 2022
Article in press: October 2, 2022
Published online: November 15, 2022
Processing time: 111 Days and 19.3 Hours
For optimizing fecal immunochemical test (FIT)-based screening programs, reducing the rate of missed colorectal cancers (CRCs) by FIT (FIT-interval CRCs) is an important aspect. Knowledge of the molecular make-up of these missed lesions could facilitate more accurate detection of all (precursor) lesions.
To compare the molecular make-up of FIT-interval CRCs to lesions that are detected by FIT [screen-detected CRCs (SD-CRCs)].
FIT-interval CRCs observed in a Dutch pilot-program of FIT-based screening were compared to a control group of SD-CRCs in a 1:2 ratio, resulting in 27 FIT-interval CRC and 54 SD-CRCs. Molecular analyses included microsatellite instability (MSI), CpG island methylator phenotype (CIMP), DNA sequence mutations and copy number alterations (CNAs).
Although no significant differences were reached, FIT-interval CRCs were more often CIMP positive and MSI positive (33% CIMP in FIT-interval CRCs vs 21% in SD-CRCs (P = 0.274); 19% MSI in FIT-interval CRCs vs 12% in SD-CRCs (P = 0.469)), and showed more often serrated pathway associated features such as BRAF (30% vs 12%, P = 0.090) and PTEN (15% vs 2.4%, P = 0.063) mutations. APC mutations, a classic feature of the adenoma-carcinoma-sequence, were more abundant in SD-CRCs (68% vs 40% in FIT-interval CRCs P = 0.035). Regarding CNAs differences between the two groups; FIT-interval CRCs less often showed gains at the regions 8p11.22-q24.3 (P = 0.009), and more often gains at 20p13-p12.1 (P = 0.039).
Serrated pathway associated molecular features seem to be more common in FIT-interval CRCs, while classic adenoma carcinoma pathway associated molecular features seem to be more common in SD-CRCs. This indicates that proximal serrated lesions may be overrepresented among FIT-interval CRCs.
Core Tip: Fecal immunochemical test (FIT) is effective in reducing colorectal cancer (CRC) but FIT testing is not perfect. FIT interval cancers, i.e. CRCs diagnosed after a negative FIT but before the next FIT invitation, still occur. Previous studies have shown that FIT sensitivity for sessile serrated lesions (SSLs) is low, but a correlation between the occurrence of FIT interval cancers and the serrated pathway has not been established. In our study, the serrated pathway-associated molecular features were more common in FIT-interval CRCs as compared to screen detected CRCs. This indicates that proximal serrated lesions may be overrepresented among FIT interval CRCs. The findings of this study can provide guidance on strategies to further improve stool-based CRC screening with incorporating biomarkers for SSLs, thereby reducing the number of screening interval CRCs.