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Mucinous adenocarcinoma of the colon is defined by extracellular mucin occupying at least 50% of the tumour. Although it is often regarded as a distinct histological subtype, its clinicopathological profile remains variable across published series. We compared mucinous and classic adenocarcinoma in a colon-only surgical cohort.

We retrospectively reviewed patients who underwent oncological resection for colon adenocarcinoma between October 2021 and March 2026. Rectal tumours, neoadjuvant-treated cases and signet ring cell carcinoma were excluded. Clinicopathological variables were compared using Mann-Whitney U, Pearson chi-square or Fisher exact tests. Multivariable analyses were revised as parsimonious logistic regression models, with model size and event counts reported.

The final cohort included 155 colon cancers: 29 mucinous and 126 classic adenocarcinomas. Mucinous tumours were more often right-sided (75.9% vs. 44.4%; p = 0.002) and more frequently poorly differentiated (24.1% vs. 4.8%; p = 0.003). Advanced pT stage was common in both groups (86.2% vs. 82.5%; p = 0.786). Nodal metastasis was numerically less frequent in mucinous adenocarcinoma (31.0% vs. 50.8%; p = 0.055), while lymphovascular invasion was significantly less common (10.3% vs. 32.5%; p = 0.017). Deficient mismatch repair was recorded in 13.8% of mucinous tumours and 8.7% of classic adenocarcinomas (p = 0.484). In parsimonious adjusted models, mucinous histology was not independently associated with advanced pT stage (adjusted OR 1.51, 95% CI 0.46-4.92; p = 0.496) or nodal metastasis (adjusted OR 0.48, 95% CI 0.19-1.19; p = 0.113).

In this colon-only cohort, mucinous adenocarcinoma was associated with right-sided location and poor differentiation, but not with independently higher local invasion or nodal spread. These findings support a cautious, clinicopathology-based interpretation of mucinous histology and should not be extrapolated to prognosis without molecular and survival data.