Table 3

Molecular characteristics of colorectal cancer according to tumour location bowel subsite

Molecular featureTotal NCaecumAscending colonHepatic flexureTransverse colonSplenic flexureDescending colonSigmoid colonRectosigmoidRectump Value
CIMP status<0.0001
 CIMP-low/zero1010 (83%)160 (78%)152 (60%)24 (65%)54 (70%)24 (86%)68 (92%)266 (96%)85 (98%)177 (98%)
 CIMP-high208 (17%)44 (22%)102 (40%)13 (35%)23 (30%)4 (14%)6 (8.1%)10 (3.6%)2 (2.3%)4 (2.2%)
MSI status<0.0001
 MSS1061 (84%)163 (78%)165 (63%)27 (71%)64 (80%)25 (81%)70 (93%)275 (97%)87 (97%)183 (98%)
 MSI-high196 (16%)46 (22%)98 (37%)11 (29%)16 (20%)6 (19%)5 (6.7%)8 (2.8%)3 (3.3%)3 (1.6%)
BRAF mutation<0.0001
 (−)1093 (86%)186 (88%)172 (64%)25 (68%)62 (78%)25 (81%)68 (89%)276 (96%)90 (96%)189 (98%)
 (+)183 (14%)26 (12%)95 (36%)12 (32%)18 (23%)6 (19%)8 (11%)11 (3.8%)4 (4.3%)3 (1.6%)
KRAS mutation<0.0001
 (−)819 (64%)101 (48%)182 (68%)26 (70%)59 (73%)21 (66%)50 (66%)186 (65%)63 (68%)131 (68%)
 (+)458 (36%)111 (52%)85 (32%)11 (30%)22 (27%)11 (34%)26 (34%)101 (35%)30 (32%)61 (32%)
PIK3CA mutation0.0016
 (−)962 (82%)146 (75%)191 (78%)31 (84%)62 (85%)18 (64%)57 (80%)220 (83%)77 (90%)160 (89%)
 (+)217 (18%)49 (25%)54 (22%)6 (16%)11 (15%)10 (36%)14 (20%)44 (17%)9 (10%)20 (11%)
LINE-1 methylation level (mean±SD)
62.7±9.563.7±9.064.7±9.462.4±8.762.5±10.061.9±10.260.2±11.761.3±9.161.0±10.163.2±8.50.0003
ABCB1 expression level (log2 intensity)
 Median (IQR)6.47 (6.35–6.81)6.46 (6.35–6.71)6.43 (6.35–6.73)6.43 (6.35–6.68)6.44 (6.35–6.67)6.48 (6.38–6.91)6.60 (6.36–6.84)6.51 (6.37–6.91)6.53 (6.35–6.82)6.51 (6.39–6.80)0.19
  • (%) Indicates the proportion of cases with a specific molecular feature among cancers located in each subsite (caecum, ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon, rectosigmoid or rectum). p Values were calculated by the χ2 test, except for LINE-1 (one-way analysis of variance test) and ABCB1 (Kruskal–Wallis test).

  • CIMP, CpG island methylator phenotype; MSI, microsatellite instability; MSS, microsatellite stable.