# Colon cancer (adenocarcinoma of the colon)

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

## TL;DR

Colon cancer is bowel cancer arising in the large bowel above the rectum. It shares its biology with colorectal cancer but is treated differently from rectal cancer: surgery comes first without radiotherapy, chemotherapy afterwards is decided by stage and increasingly by a blood test for leftover tumour DNA, and the side the tumour started on changes which drugs work once it has spread.

## Summary

The WHO classification of digestive tumours describes adenocarcinoma of the colon and rectum as one chapter, with the site recorded because staging and local treatment differ (Nagtegaal 2020). The colorectal page holds the molecular subtypes; this page is the anatomical entity that the corpus's rectal cancer page mirrors. Two identically designed adjuvant trials in 855 colon and 796 rectal cancer patients showed that adding folinic acid to fluorouracil improved seven-year overall survival in colon but not rectal cancer, with different patterns of recurrence (Clinical Colorectal Cancer 2013). Within the colon, right-sided (proximal) tumours are more often mismatch-repair deficient, BRAF-mutant, mucinous and worse-prognosis in the metastatic setting, and left-sided tumours respond better to EGFR antibodies; a pooled analysis of 2,879 metastatic patients found no outcome difference between left-sided colon and rectal primaries (European Journal of Cancer 2018).

How it differs from its parent: the colorectal page carries the shared biology and the metastatic drug pathways; colon cancer differs from rectal cancer in having no role for pelvic radiotherapy, in colectomy with regional lymphadenectomy as the operation, and in the stage III adjuvant standard of three or six months of FOLFOX or CAPOX set by the IDEA collaboration and recorded on the FOLFOX and CAPOX pages.

How common: no separate GLOBOCAN figure; the proximal-colon share above is from one registry.

Treatment follows the colorectal page and the NCI PDQ colon summary: colectomy for stage I to III, adjuvant FOLFOX or CAPOX for stage III and high-risk stage II, with the ctDNA-guided DYNAMIC and CIRCULATE-US trials and the exercise trial CHALLENGE linked here; mismatch-repair deficient colon cancer is treated with checkpoint inhibitors before surgery in NICHE-2 and after surgery in ATOMIC; metastatic disease follows the colorectal page by sidedness and RAS, BRAF and HER2 status.

## Fields

- Kind: Cancer
- Last checked: 2026-09-24
- Also known as: Colon cancer; Colonic adenocarcinoma; Cancer of the colon; Right-sided and left-sided colon cancer; Rectal vs colon (different local therapy)
- Tags: subtype-page; wave4; colorectal
- Group: gastrointestinal
- Burden: GLOBOCAN counts colon and rectum together (1,926,425 new colorectal cancers in 2022); most colorectal cancers arise in the colon. In the Munich registry, 34 percent of ordinary adenocarcinomas were in the proximal colon (J Cancer Res Clin Oncol 2016).
- Subtypes: Right-sided (proximal) colon cancer: caecum to transverse colon; more often MSI-high, BRAF-mutant and mucinous; Left-sided (distal) colon cancer: splenic flexure to sigmoid; EGFR-antibody responsive when RAS wild-type; Stage II colon cancer (ctDNA-guided adjuvant decisions); Stage III colon cancer (three or six months of FOLFOX or CAPOX); Mismatch-repair deficient colon cancer (neoadjuvant immunotherapy in trials)
- Biomarkers: Mismatch repair and microsatellite instability; RAS and BRAF V600E mutation, HER2 amplification (metastatic); Primary tumour side; Circulating tumour DNA after surgery; Carcinoembryonic antigen

## 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/colon-cancer/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/colon-cancer/#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/colon-cancer/#what-it-is [5 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/colon-cancer/#finding-it [5 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/colon-cancer/#treating-it [3 settings, 3 decisions 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/colon-cancer/#evidence [8 trials]
- 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/colon-cancer/#science [4 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/colon-cancer/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/colon-cancer/#living-with-it [15 questions, 6 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/colon-cancer/coming/ [10 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/colon-cancer/data/ [36 connected records]

## Standard of care

- Stage I to III: Colectomy with regional lymphadenectomy; adjuvant FOLFOX or CAPOX for stage III and high-risk stage II, with ctDNA guidance under study. ([FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [CAPOX (capecitabine, oxaliplatin)](https://onco.cc/drugs/capox/), [DYNAMIC](https://onco.cc/trials/dynamic/), [CIRCULATE-US](https://onco.cc/trials/circulate-us/), [CHALLENGE (CCTG CO.21)](https://onco.cc/trials/challenge/))
- Mismatch-repair deficient, localised: Neoadjuvant nivolumab and ipilimumab (NICHE-2) and adjuvant atezolizumab with FOLFOX (ATOMIC) in trials. ([NICHE-2](https://onco.cc/trials/niche-2/), [ATOMIC (Alliance A021502)](https://onco.cc/trials/atomic/), [Nivolumab](https://onco.cc/drugs/nivolumab/), [Ipilimumab](https://onco.cc/drugs/ipilimumab/))
- Metastatic: As the colorectal page by sidedness and RAS, BRAF and HER2 status. ([Colorectal cancer](https://onco.cc/cancers/colorectal/), [Cetuximab](https://onco.cc/drugs/cetuximab/), [Panitumumab](https://onco.cc/drugs/panitumumab/), [Bevacizumab](https://onco.cc/drugs/bevacizumab/), [PARADIGM](https://onco.cc/trials/paradigm/))

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Colorectal_cancer
- NCI PDQ: colon cancer treatment: https://www.cancer.gov/types/colorectal/patient/colon-treatment-pdq
- Nagtegaal 2020, Histopathology: the 2019 WHO classification of tumours of the digestive system: https://doi.org/10.1111/his.13975
- Clinical Colorectal Cancer 2013: two adjuvant trials reveal differences between colon and rectal cancer: https://doi.org/10.1016/j.clcc.2012.07.005
- European Journal of Cancer 2018: left-sided colon and rectal cancer in 2,879 ARCAD trial patients: https://doi.org/10.1016/j.ejca.2018.08.020
- J Cancer Res Clin Oncol 2016: mucinous and signet ring cell colorectal cancer in 28,056 Munich registry patients: https://doi.org/10.1007/s00432-016-2224-2

## Connected records

- cancers: [BRAF V600E-mutant colorectal cancer](https://onco.cc/cancers/braf-v600e-colorectal/), [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Medullary carcinoma of the colon](https://onco.cc/cancers/colorectal-medullary-carcinoma/), [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/), [Rectal cancer](https://onco.cc/cancers/rectal-cancer/), [Serrated adenocarcinoma of the colon and rectum](https://onco.cc/cancers/colorectal-serrated-adenocarcinoma/), [Signet ring cell carcinoma of the colon and rectum](https://onco.cc/cancers/colorectal-signet-ring-cell-carcinoma/)
- drugs: [Bevacizumab](https://onco.cc/drugs/bevacizumab/), [Capecitabine](https://onco.cc/drugs/capecitabine/), [CAPOX (capecitabine, oxaliplatin)](https://onco.cc/drugs/capox/), [Cetuximab](https://onco.cc/drugs/cetuximab/), [Fluorouracil (5-FU)](https://onco.cc/drugs/fluorouracil/), [FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [Ipilimumab](https://onco.cc/drugs/ipilimumab/), [Nivolumab](https://onco.cc/drugs/nivolumab/), [Oxaliplatin](https://onco.cc/drugs/oxaliplatin/), [Panitumumab](https://onco.cc/drugs/panitumumab/)
- trials: [ALASCCA](https://onco.cc/trials/alascca/), [ATOMIC (Alliance A021502)](https://onco.cc/trials/atomic/), [CHALLENGE (CCTG CO.21)](https://onco.cc/trials/challenge/), [CIRCULATE-US](https://onco.cc/trials/circulate-us/), [CRYSTAL & FIRE-3](https://onco.cc/trials/crystal-fire3/), [DYNAMIC](https://onco.cc/trials/dynamic/), [NICHE-2](https://onco.cc/trials/niche-2/), [PARADIGM](https://onco.cc/trials/paradigm/)

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JSON: https://onco.cc/api/v1/entities/colon-cancer.json