Table 1 Clinical and molecular characteristics of colon cancer according to microsatellite instability (MSI) or CpG island methylator phenotype (CIMP) status
Clinical or molecular featureAll casesMSI-highMSSCIMP-high*CIMP-low†CIMP-0‡
Total number649121528126252271
Sex
    Male (HPFS)283 (44%)43 (36%)240 (45%)40 (32%)125 (50%)118 (44%)
    Female (NHS)366 (56%)78 (64%)288 (55%)86 (68%)127 (50%)153 (56%)
p = 0.05p = 0.004
Mean age (SD)66.5 (8.2)68.1 (7.3)66.2 (8.4)69.5 (6.8)66.4 (8.2)65.3 (8.5)
p = 0.01§p<0.0001§,¶
Year of diagnosis
    Prior to 1990101 (16%)13 (11%)88 (17%)9 (7.1%)43 (17%)49 (18%)
    1990 to 1999473 (73%)95 (79%)378 (71%)102 (81%)184 (73%)187 (69%)
    2000 to 200275 (12%)13 (11%)62 (12%)15 (12%)25 (9.9%)35 (13%)
p = 0.23p = 0.14
Tumour location
    Proximal371 (58%)102 (85%)269 (52%)114 (90%)153 (62%)104 (39%)
    Distal269 (42%)18 (15%)251 (48%)12 (9.5%)94 (38%)163 (61%)
p<0.0001p<0.0001
Tumour stage
    I137 (21%)19 (16%)118 (22%)14 (11%)55 (22%)68 (25%)
    II216 (33%)70 (58%)146 (28%)66 (52%)64 (25%)86 (32%)
    III165 (25%)22 (18%)143 (27%)24 (19%)69 (27%)72 (27%)
    IV83 (13%)5 (4.1%)78 (15%)16 (13%)40 (16%)27 (10%)
    Unknown48 (7.4%)5 (4.1%)43 (8.1%)6 (4.8%)24 (9.5%)18 (6.6%)
p<0.0001p<0.0001
Tumour grade
    Low574 (89%)86 (71%)488 (93%)86 (68%)232 (92%)256 (95%)
    High72 (11%)35 (29%)37 (7.0%)40 (32%)19 (7.6%)13 (4.8%)
p<0.0001p<0.0001
KRAS mutation
    (−)409 (63%)102 (84%)307 (58%)109 (87%)131 (52%)169 (63%)
    (+)238 (37%)19 (16%)219 (42%)17 (13%)120 (48%)101 (37%)
p<0.0001p<0.0001
BRAF mutation
    (−)526 (83%)65 (55%)461 (90%)49 (40%)221 (90%)256 (97%)
    (+)105 (17%)53 (45%)52 (10%)74 (60%)24 (9.8%)7 (2.7%)
p<0.0001p<0.0001
CIMP
    CIMP-0271 (42%)12 (9.9%)259 (49%)
    CIMP-low252 (39%)21 (17%)231 (44%)
    CIMP-high126 (19%)88 (73%)38 (7.2%)
p<0.0001
  • % indicates the proportion of tumours with a specific clinical or molecular feature in a given subtype.

  • Proximal colon includes caecum to transverse colon, and distal colon includes splenic flexure to sigmoid colon.

  • *Six to eight methylated promoters.

  • †One to five methylated promoters.

  • ‡No methylated promoters.

  • §The t test assuming unequal variances was used to compare mean ages.

  • ¶Compared to combined CIMP-low/CIMP-0.

  • HPFS, Health Professionals Follow-up Study; MSS, microsatellite stable; NHS, Nurses’ Health Study; SD, standard deviation.