# Serrated adenocarcinoma of the colon and rectum

Source: https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/  
OnCo record `colorectal-serrated-adenocarcinoma` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Serrated adenocarcinoma is a form of bowel cancer that grows out of sessile serrated polyps rather than ordinary adenomas, keeping their saw-tooth pattern. Most cases carry a KRAS or BRAF mutation and the BRAF-mutant ones are often mismatch-repair deficient. It is treated like other bowel cancer, with the BRAF and mismatch repair results guiding drugs when it has spread.

## Summary

The WHO classification recognises serrated adenocarcinoma as a colorectal adenocarcinoma type with serrated glands, eosinophilic cytoplasm and vesicular nuclei, arising through the serrated pathway of sessile serrated lesions and traditional serrated adenomas (Nagtegaal 2020). In 42 serrated adenocarcinomas, KRAS and BRAF mutations were present in 45 and 33 percent against 27 and 0 percent of non-serrated carcinomas; BRAF mutation was specific for serrated adenocarcinoma and marked a subset with gene methylation and a tendency to microsatellite instability, while the high KRAS rate suggests many KRAS-mutant colorectal cancers arise from serrated precursors (Histopathology 2011). In 89 cases KRAS mutation (42.7 percent) was more prevalent than BRAF (25.8 percent), MGMT loss was more frequent than in conventional carcinoma (50.6 against 25.3 percent), and most serrated adenocarcinomas were microsatellite stable, differing from sporadic MSI-high carcinomas (International Journal of Cancer 2012).

How it differs from its parent: its precursor is the sessile serrated lesion rather than the adenoma, so it is the histology behind the right-sided BRAF-mutant and CpG island methylator cancers on the colorectal and BRAF pages, and its KRAS-mutant, microsatellite-stable majority has a worse outlook than the MSI-high minority.

How common: no registry share was found in the sources read.

Treatment: as the colorectal page by stage, BRAF, RAS and mismatch repair status (encorafenib with cetuximab for BRAF V600E metastatic disease; checkpoint inhibitors for MSI-high); there is no trial in the histology.

## Fields

- Kind: Cancer
- Last checked: 2026-09-24
- Also known as: Serrated adenocarcinoma; Serrated pathway colorectal cancer; Colorectal carcinoma arising from a sessile serrated lesion
- Tags: subtype-page; wave4; colorectal
- Group: gastrointestinal
- Burden: The defining series compared 42 and 89 serrated adenocarcinomas with conventional carcinomas (Histopathology 2011; International Journal of Cancer 2012); no registry share was found in the sources read, and the serrated pathway is thought to account for a larger share of colorectal cancer than the strictly defined histology.
- Subtypes: BRAF-mutant serrated adenocarcinoma (methylated; often MSI-high; right-sided); KRAS-mutant serrated adenocarcinoma (microsatellite stable; the majority); Serrated adenocarcinoma arising in a traditional serrated adenoma
- Biomarkers: BRAF V600E and KRAS mutation; Mismatch repair status and MLH1 methylation; MGMT loss; CpG island methylator phenotype (research)

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/colorectal-serrated-adenocarcinoma/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/#overview
- What it is (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/#what-it-is [3 subtypes]
- Finding it (on the hub): How it shows itself, how it is confirmed, what screening exists, and the biomarkers clinicians test for. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/#finding-it [4 biomarkers]
- Treating it (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/#treating-it [1 setting, 1 decision with options]
- Evidence (on the hub): Trials recruiting now, the landmark trials, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/#evidence
- The science (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/#science [3 targets]
- Where you are (own page): Cases by country, the UK and NHS pathway and other country lenses, and the expert centres with trials on record. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/where-you-are/
- Living with it (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/#living-with-it [8 questions, 4 red cards]
- What is coming (own page): Everything in development, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/coming/ [2 medicines]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/data/ [10 connected records]

## Standard of care

- All stages: Treated as the colorectal page by stage and molecular status: encorafenib with cetuximab for BRAF V600E metastatic disease, checkpoint inhibitors for MSI-high disease. ([Colorectal cancer](https://onco.cc/cancers/colorectal/), [BRAF V600E-mutant colorectal cancer](https://onco.cc/cancers/braf-v600e-colorectal/), [Encorafenib](https://onco.cc/drugs/encorafenib/), [Cetuximab](https://onco.cc/drugs/cetuximab/))

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Sessile_serrated_lesion
- Nagtegaal 2020, Histopathology: the 2019 WHO classification of tumours of the digestive system: https://doi.org/10.1111/his.13975
- Histopathology 2011: KRAS and BRAF mutations in colorectal serrated adenocarcinoma: https://doi.org/10.1111/j.1365-2559.2011.03821.x
- International Journal of Cancer 2012: serrated adenocarcinoma, oncogene mutations and MSI in 89 cases: https://doi.org/10.1002/ijc.27454

## Connected records

- cancers: [BRAF V600E-mutant colorectal cancer](https://onco.cc/cancers/braf-v600e-colorectal/), [Colon cancer (adenocarcinoma of the colon)](https://onco.cc/cancers/colon-cancer/), [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Mismatch-repair deficient (MSI-high) colorectal cancer](https://onco.cc/cancers/msi-high-colorectal/), [Mucinous adenocarcinoma of the colon and rectum](https://onco.cc/cancers/colorectal-mucinous-adenocarcinoma/)
- targets: [BRAF](https://onco.cc/targets/braf/), [KRAS](https://onco.cc/targets/kras/)
- drugs: [Cetuximab](https://onco.cc/drugs/cetuximab/), [Encorafenib](https://onco.cc/drugs/encorafenib/)

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JSON: https://onco.cc/api/v1/entities/colorectal-serrated-adenocarcinoma.json