Table 3.
Frequency of PIK3CA Mutation in Colorectal Cancer According to Various Molecular Features.
| Molecular Feature | n | PIK3CA Mutation [n (%)] | OR (95% CI) | P |
| MSI status | ||||
| MSS | 458 | 65 (14%) | 1 | |
| MSI-low | 52 | 11 (21%) | 1.62 (0.79–3.32) | |
| MSI-high | 74 | 15 (20%) | 1.54 (0.82–2.87) | |
| CIMP status | ||||
| CIMP-0 | 279 | 33 (12%) | 1 | Referent |
| CIMP-low | 233 | 41 (18%) | 1.59 (0.97–2.61) | |
| CIMP-high | 78 | 17 (22%) | 2.08 (1.09–3.97) | .03 |
| MSI/CIMP status | ||||
| Non-MSI-high CIMP-low/0 | 485 | 69 (14%) | 1 | |
| MSI-high CIMP-low/0 | 21 | 5 (24%) | 1.88 (0.67–5.31) | |
| Non-MSI-high CIMP-high | 25 | 7 (28%) | 2.34 (0.94–5.82) | |
| MSI-high CIMP-high | 53 | 10 (19%) | 1.40 (0.67–2.92) | |
| KRAS mutation | ||||
| (-) | 365 | 38 (10%) | 1 | Referent |
| (+) | 223 | 53 (24%) | 2.68 (1.70–4.23) | <.0001 |
| BRAF mutation | ||||
| (-) | 505 | 79 (16%) | 1 | |
| (+) | 71 | 10 (14%) | 0.88 (0.43–1.80) | |
| p53 expression | ||||
| (-) | 327 | 60 (18%) | 1 | Referent |
| (+) | 257 | 28 (11%) | 0.54 (0.34–0.88) | .01 |
| 18q LOH | ||||
| (-) | 148 | 25 (17%) | 1 | |
| (+) | 168 | 18 (11%) | 0.59 (0.31–1.13) | |
| β-Catenin score* | ||||
| 0–2 (inactive) | 321 | 61 (19%) | 1 | Referent |
| 3–5 (active) | 184 | 17 (9.2%) | 0.43 (0.25–0.77) | .004 |
| FASN expression | ||||
| (-) | 222 | 24 (11%) | 1 | Referent |
| (+) | 355 | 65 (18%) | 1.85 (1.12–3.05) | .02 |
| Phospho-RPS6 | ||||
| (-) | 323 | 41 (13%) | 1 | Referent |
| (+) | 149 | 36 (24%) | 2.19 (1.33–3.61) | .002 |
CI indicates confidence interval; CIMP, CpG island methylator phenotype; FASN, fatty acid synthase; LOH, loss of heterozygosity; MSI, microsatellite instability; MSS, microsatellite stable; OR, odds ratio; RPS6, ribosomal protein S6.
*
β-Catenin score is the sum of nuclear, cytolasmic, and membrane score as described by Jass et al. [37].