Table 2b. Molecular characteristics of colorectal cancer cases in the CRUMS cohort.
| N | MSI | MSS | P-value | CIMP-negative | CIMP-low | CIMP-high | P-value | |
|---|---|---|---|---|---|---|---|---|
| Frequency (%) |
414 |
62 (15.5) |
338 (84.5) |
|
209 (50.6) |
155 (37.5) |
49 (11.9) |
|
| Quadruple Index |
|
|
|
<0.0001 |
|
|
|
<0.0001 |
| Negative | 227 (56.0) | 19 (31.7) | 201 (60.5) | 142 (69.3) | 82 (54.3) | 3 (6.3) | ||
| Positive |
178 (44.0) |
41 (68.3) |
131 (39.5) |
|
63 (30.7) |
69 (45.7) |
45 (93.8) |
|
| KRAS | 0.002 | 0.001 | ||||||
| Wt | 331 (80.5) | 59 (95.2) | 263 (78.3) | 174 (83.7) | 111 (72.1) | 46 (93.9) | ||
| Mutant |
80 (19.5) |
3 (4.8) |
73 (21.7) |
|
34 (16.3) |
43 (27.9) |
3 (6.1) |
|
| BRAF | <0.0001 | <0.0001 | ||||||
| Wt | 356 (86.8) | 27 (44.3) | 317 (94.6) | 206 (99.0) | 143 (92.9) | 7 (14.6) | ||
| Mutant |
54 (13.2) |
34 (55.7) |
18 (5.4) |
|
2 (1.0) |
11 (7.1) |
41 (85.4) |
|
|
PIK3CA Exon20 |
|
|
|
0.013 |
|
|
|
0.006 |
| Wt | 396 (97.8) | 55 (93.2) | 328 (98.5) | 204 (99.0) | 150 (98.0) | 42 (91.3) | ||
| Mutant |
9 (2.2) |
4 (6.8) |
5 (1.5) |
|
2 (1.0) |
3 (2.0) |
4 (8.7) |
|
| PTEN |
|
|
|
0.719 |
|
|
|
0.729 |
| Normal | 352 (85.9) | 52 (83.9) | 286 (85.6) | 178 (85.6) | 134 (87.6) | 40 (83.3) | ||
| Loss | 58 (14.1) | 10 (16.1) | 48 (14.4) | 30 (14.4) | 19 (12.4) | 8 (16.7) |
Abbreviations: CIMP=CpG island methylator phenotype; CRUMS=Colorectal Cancer in Umeå Study; MSI=microsatellite instability; MSS=microsatellite stable; Wt=wild-type.
The following numbers of missing cases were present in CRUMS: CIMP status,1; Quadruple Index, 9; KRAS mutation status, 3; BRAF mutation status, 4; PIK3CA mutation status, 9; PTEN mutation status, 4. Cases lacking nuclear staining of tumor cells for at least one of MLH1, MSH2, MSH6 or PMS2 were considered to have a positive MSI screening status (MSI). CIMP according to an eight-gene panel including CDKN2A, hMLH1, CACNA1G, NEUROG1, RUNX3, SOCS1, IGF2 and CRABP1; CIMP-negative, 0 genes hypermethylated; CIMP-low, 1–5 genes hypermethylated; CIMP-high, 6–8 genes hypermethylated. Kruskall–Wallis test was used for continuous variables, χ2-test or Fisher's exact test used for categorical variables.