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Use of multivariate analysis to suggest a new molecular classification of colorectal cancer
Author(s) -
Domingo Enric,
Ramamoorthy Rajarajan,
Oukrif Dahmane,
Rosmarin Daniel,
Presz Michal,
Wang Haitao,
Pulker Hannah,
Lockstone Helen,
Hveem Tarjei,
Cranston Treena,
Danielsen Havard,
Novelli Marco,
Davidson Brian,
Xu ZhengZhou,
Molloy Peter,
Johnstone Elaine,
Holmes Christopher,
Midgley Rachel,
Kerr David,
Sieber Oliver,
Tomlinson Ian
Publication year - 2013
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.4139
Subject(s) - kras , neuroblastoma ras viral oncogene homolog , microsatellite instability , colorectal cancer , mutation , biology , cancer , oncology , medicine , cancer research , gnas complex locus , genetics , gene , allele , microsatellite
Molecular classification of colorectal cancer ( CRC ) is currently based on microsatellite instability ( MSI ), KRAS or BRAF mutation and, occasionally, chromosomal instability ( CIN ). Whilst useful, these categories may not fully represent the underlying molecular subgroups. We screened 906 stage II / III CRCs from the VICTOR clinical trial for somatic mutations. Multivariate analyses (logistic regression, clustering, Bayesian networks) identified the primary molecular associations. Positive associations occurred between: CIN and TP53 mutation; MSI and BRAF mutation; and KRAS and PIK3CA mutations. Negative associations occurred between: MSI and CIN ; MSI and NRAS mutation; and KRAS mutation, and each of NRAS , TP53 and BRAF mutations. Some complex relationships were elucidated: KRAS and TP53 mutations had both a direct negative association and a weaker, confounding, positive association via TP53 – CIN–MSI – BRAF–KRAS . Our results suggested a new molecular classification of CRCs : (1) MSI + and/or BRAF ‐mutant; (2) CIN + and/or TP53 – mutant, with wild‐type KRAS and PIK3CA ; (3) KRAS ‐ and/or PIK3CA ‐mutant, CIN + , TP53 ‐wild‐type; (4) KRAS – and/or PIK3CA ‐mutant, CIN – , TP53 ‐wild‐type; (5) NRAS ‐mutant; (6) no mutations; (7) others. As expected, group 1 cancers were mostly proximal and poorly differentiated, usually occurring in women. Unexpectedly, two different types of CIN + CRC were found: group 2 cancers were usually distal and occurred in men, whereas group 3 showed neither of these associations but were of higher stage. CIN + cancers have conventionally been associated with all three of these variables, because they have been tested en masse . Our classification also showed potentially improved prognostic capabilities, with group 3, and possibly group 1, independently predicting disease‐free survival. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.