Our previous analyses suggest that smoking status may be differentially associated with the incidence of colorectal cancer by tumour status of CIMP, BRAF mutation and T lymphocyte infiltrates.14 19 Therefore, we conducted additional analyses stratified by tumour status of CIMP, BRAF mutation or lymphocytic reaction, which yielded similar differential associations, though statistical power was limited in the respective strata (online supplemental table S9). Here, BRAF is linked to colorectal cancer.