Unique clinicopathologic and genetic alteration features in early onset colorectal carcinoma compared with age-related colorectal carcinoma: a large cohort next generation sequence analysis

Early age of onset is an independent predictor for worse disease-free survival in sporadic rectal cancer patients. A comparative analysis of 980 consecutive patients

BACKGROUND

while interest on early-onset colorectal cancer (age ≤49) is on the rise, studies on early-onset rectal cancer (EORC) are limited. The aim of this study was to compare predictors for disease progression/recurrence between sporadic EORC and late-onset RC patients (LORC).

METHODS

163 EORC and 830 LORC operated between January 1st^, 2010 and April 30th^, 2021 at a tertiary center were included. Demographics, tumor characteristics, microsatellite status, gene mutations (KRAS, BRAF, NRAS, PI3Kca) and oncologic outcomes were compared. A Cox proportional hazards regression analysis was performed to ascertain the effect of variables on recurrence/progression and death. Recurrence/Progression free survival (R/PFS) and cancer specific survival (CSS) were analyzed by the Kaplan-Meier estimator.

RESULTS

Mean age of EORC was 42.16, (46% aged 45-49). A majority of EORC patients had a family history for CRC (p = 0.01) and underwent total neoadjuvant treatment (p = 0.01). EORC patients showed a higher rate of low-grade tumor differentiation (p < 0.0001), stage III-IV (p = 0.001), microsatellite instability (p = 0.02), locoregional nodal (p = 0.001) and distant metastases (p < 0.0001). Accordingly, more EORC patients underwent adjuvant treatment (p < 0.0001). Mutations were mostly reported among LORC cases (p = 0.04), whereas EORC patients showed a worse R/PFS (p = 0.02), even at stage I (p = 0.04). CSS did not differ (p = 0.11) across groups. Multivariate analysis indicated age of onset (p = 0.04) was an independent predictor for progression/recurrence.

CONCLUSIONS

Age of onset was shown to be an independent unfavorable predictor. Delayed diagnosis could explain this effect in the more advanced stages, while the worse outcomes in stage I may suggest a more aggressive disease behavior.

Clinicopathologic Characteristics of FBXW7-Mutated Colorectal Adenocarcinoma and Association with Aberrant Beta-catenin Localization

Oncogenic mutations in the adenomatous polyposis coli (APC)/Wnt signaling pathway are well documented. The FBXW7 gene (F-Box And WD Repeat Domain Containing 7) encodes a member of the ubiquitin-proteasome complex that is more recently described to antagonize the oncogenic Wnt pathway by promoting the degradation of β-catenin encoded by CTNNB1 gene. The pathologic significance of FBXW7 mutation in colorectal carcinoma (CRC) remains underreported. In this study, we report the clinicopathologic and β-catenin immunohistochemical features of a single-institution cohort (83 cases) of FBXW7-mutated CRC compared to CTNNB1-mutated CRC. FBXW7-mutated CRC was more common in older patients (p=0.031) and in the left/distal colon (p=0.022). Immunohistochemical analysis revealed that aberrant nuclear/cytoplasmic β-catenin localization was identified in a significantly high proportion of FBXW7-mutated CRCs. When compared to CTNNB1-mutated CRC, FBXW7-mutated CRC showed a significantly higher proportion of MSI-stable tumors with intact expression of DNA mismatch repair proteins, and had significantly more frequent co-occurrence of missense TP53 and KRAS mutations. The most frequently mutated FBXW7 residues/hotspots were located within the WD repeat domains (aa 378-659), which were also associated with aberrant nuclear/cytoplasmic localization of β-catenin protein. Our results indicate the unique pathologic characteristics of FBXW7 mutated CRC with frequent co-occurrence of missense mutant TP53, and KRAS. The mutated FBXW7 residues/hotspots and its association with aberrant nuclear/cytoplasmic β-catenin localization further support the oncogenic role of FBXW7 in colon carcinogenesis.

Recent Updates on the Significance of KRAS Mutations in Colorectal Cancer Biology

The most commonly mutated isoform of RAS among all cancer subtypes is KRAS. In this review, we focus on the special role of KRAS mutations in colorectal cancer (CRC), aiming to collect recent data on KRAS-driven enhanced cell signalling, in vitro and in vivo research models, and CRC development-related processes such as metastasis and cancer stem cell formation. We attempt to cover the diverse nature of the effects of KRAS mutations on age-related CRC development. As the incidence of CRC is rising in young adults, we have reviewed the driving forces of ageing-dependent CRC.