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. 2026 Feb 21;27(4):2038.
doi: 10.3390/ijms27042038.

Analysis of Consensus Molecular Subtypes of Colorectal Cancer in Oman with Clinicopathologic Correlation

Shaista Rehman  1 , Asem Shalaby  2   3 , Said A Al-Busafi  4 , Moon Fai Chan  1 , Shaima Al Khabouri  5 , Mustafa Al Hinai  1 , Adhari Al Zaabi  6 , Mohammad Al Masqari  7 , Asim Qureshi  2 , Mohammed Al-Azri  1
Affiliations

Analysis of Consensus Molecular Subtypes of Colorectal Cancer in Oman with Clinicopathologic Correlation

Shaista Rehman et al. Int J Mol Sci. .

Abstract

Colorectal cancer (CRC) is a major public health challenge in Oman and a leading cause of cancer-related mortality. The rising incidence has been associated with lifestyle changes, urbanization, and genetic factors. The CRC Subtyping Consortium has defined four consensus molecular subtypes (CMS1-CMS4); however, data on their distribution in the Gulf region, including Oman, remain limited. This study aimed to characterize the distribution of CMS subtypes in Omani CRC patients and assess their clinicopathologic correlations using a practical immunohistochemistry (IHC) panel supplemented by a limited targeted molecular approach. This study included 273 CRC patients diagnosed between 2023 and 2024 at two major referral hospitals in Muscat. Initially, the mismatch repair (MMR)-deficient tumors (dMMR) were assigned as CMS1, while the MMR-proficient (pMMR) tumors were further evaluated for β-catenin, P53, KRAS, and TGF-β expression. Mutations in BRAF, TP53, and KRAS were analyzed by sequencing. The cohort comprised 51.6% males, with a mean age of 59.1 years. Most tumors were left-sided (70.7%). dMMR (CMS1) comprised 31 cases (11.35%). Out of the pMMR tumors, 111 cases (40.65%) showed positive expression of β-catenin and P53 (CMS2), 63 cases (23.0%) showed KRAS mutations (CMS3), and 68 cases (24.9%) showed TGF-β-positive expression (CMS4). The cases were predominantly concentrated in Muscat (41%). This study demonstrated the feasibility and clinical relevance of CMS-based classification in Oman and its potential role in precision oncology and healthcare planning.

Keywords: Oman; colorectal cancer; consensus molecular subtypes; immunohistochemistry; molecular testing.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Algorithm for categorizing CMS subtypes, testing, and classification.
Figure 2
Figure 2
Representative photomicrographs of immune histochemical reactivity to different antibodies used in this study. β-catenin, example of positive reactivity (A) and negative reactivity (B); P53, positive reactivity (C) and negative reactivity (D); KRAS, positive reactivity (E) and negative reactivity (F); and TGF-β, positive reactivity (G) and negative reactivity (H). All pictures were taken at 20× magnification.
Figure 3
Figure 3
(A): Distribution of CRC cases in different regions of Oman. (B): Distribution of CMS subtypes across different regions of Oman.
See this image and copyright information in PMC

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