Early-onset colorectal cancer (under 50)
Bowel cancer is rising in people under 50, for reasons that are still not understood, and it is usually found late because neither patients nor doctors expect it. Treatment is the same as in older adults and works as well stage for stage; the changes are earlier screening, genetic testing for everyone diagnosed young, and attention to fertility, work and family.
Overview
Early-onset colorectal cancer is defined by age under 50 at diagnosis. Birth-cohort analyses (Siegel and colleagues, 2017) showed that people born around 1990 have double the colon cancer risk and four times the rectal cancer risk of those born around 1950 at the same age, a rise seen across high-income countries and attributed to diet, obesity, antibiotics, the microbiome and other early-life exposures without any one cause proven; a colibactin mutational signature from pks-positive Escherichia coli acquired in childhood is enriched in early-onset tumours (Nature 2025). About one in six patients diagnosed under 50 carries a germline cancer-predisposition variant, half of them Lynch syndrome, so multigene germline testing is recommended for everyone in this group.
Most early-onset tumours are left-sided or rectal, microsatellite-stable and diagnosed at stage III or IV after months of rectal bleeding, iron deficiency or change in bowel habit that was attributed to haemorrhoids or irritable bowel. Stage for stage, outcomes are similar to older adults, and treatment follows the same pathways: surgery and stage-based adjuvant chemotherapy, total neoadjuvant therapy or organ preservation for rectal tumours, and genotype-directed therapy for metastatic disease. Young patients receive more intensive chemotherapy without evidence that it helps them more.
The policy response has been earlier screening: the American Cancer Society lowered the starting age for average-risk adults from 50 to 45 in 2018 and the US Preventive Services Task Force followed in 2021; European programmes are debating the same step, and polygenic risk scores may set individual starting ages. For patients, the distinct needs are fertility preservation before pelvic radiotherapy and oxaliplatin, sexual and stoma counselling, financial and employment support, and enrolment in the cohort studies trying to explain the rise.
State of the art
- Screening now starts at 45 in the United States, the first policy response to the rise.
- Universal germline testing in patients under 50 finds a hereditary syndrome in about one in six.
- Mutational signatures are beginning to point at childhood exposures, including colibactin-producing bacteria.
Red cards
From the labels and guidelines behind the standard of care. Your team's thresholds win.- Emergency services nowFainting or palpitations
Fainting, near-fainting, or an irregular or racing heartbeat; several kinase inhibitors prolong the QT interval and the labels require ECG and electrolyte monitoring.
- Emergency services nowBleeding or bruising
Bleeding that will not stop, black or bloody stools, or unexplained bruising when platelets are expected to be low.
- Emergency services nowBowel perforation
Sudden severe abdominal pain, a hard or very tender abdomen, or abdominal pain with vomiting and fever. Boxed warning for gastrointestinal perforation on bevacizumab.
- Emergency services nowHypophysitis or adrenal crisis
Persistent headache with extreme tiredness, nausea, dizziness on standing or low blood pressure. Vomiting, severe weakness or collapse is adrenal crisis.
- Check before combiningEncorafenib with Tucatinib: major interaction
CYP3A4: Tucatinib (strong inhibitor) raises Encorafenib exposure (sensitive substrate).. Avoid strong and moderate inhibitors; if unavoidable, reduce to one-third (strong) or one-half (moderate) of the dose.
- Check before combiningFood and drink: Pembrolizumab
No pharmacokinetic interactions expected (antibody). See the irAE guide for toxicity management.
See all on the product pages:BevacizumabCAPOX (capecitabine, oxaliplatin)EncorafenibFOLFOX (5-FU, leucovorin, oxaliplatin)PembrolizumabSotorasibTucatinib·Printable cards in the navigator
Anatomy and lymph node drainage
- Right colon (MSI-high, BRAF commoner)
- Left colon and sigmoid
- Rectum
- Anal canal (HPV squamous)
- Appendix
- Peritoneum and omentum (mesothelioma, peritoneal spread)
- Nodes: pericolic
- Nodes: mesenteric root
- Nodes: para-aortic
- Nodes: mesorectal
- Nodes: lateral pelvic and inguinal (anal)
Right-sided tumours behave differently from left-sided and rectal ones; the colon drains along its mesenteric vessels, the rectum into the mesorectum and pelvic side wall.
- Right colon (MSI-high, BRAF commoner)Mismatch-repair deficient early-onset tumours (immunotherapy as in other dMMR disease)
- Left colon and sigmoidSporadic early-onset colorectal cancer (the large majority; mostly left colon and rectum, microsatellite-stable)
- RectumSporadic early-onset colorectal cancer (the large majority; mostly left colon and rectum, microsatellite-stable) · Hereditary early-onset colorectal cancer (Lynch syndrome, familial adenomatous polyposis and other germline variants, about one in six) · Early-onset rectal cancer (fertility, sexual function and stoma questions loom larger)
- Anal canal (HPV squamous)
- Appendix
- Peritoneum and omentum (mesothelioma, peritoneal spread)
- pericolic
- mesenteric root
- para-aortic
- mesorectal
- lateral pelvic and inguinal (anal)
Same organ: Peritoneal mesothelioma, Colorectal cancer, Rectal cancer, Mismatch-repair deficient (MSI-high) colorectal cancer, BRAF V600E-mutant colorectal cancer, HER2-amplified colorectal cancer, KRAS G12C-mutant colorectal cancer, Anal cancer (squamous cell carcinoma), Appendiceal cancer and pseudomyxoma peritonei, Small intestine cancer (small bowel adenocarcinoma)
Roughly one in ten colorectal cancers in high-income countries is now diagnosed before 50, and incidence in this age group has risen by about 2 percent a year in the United States since the mid-1990s while falling in older adults; most are left-sided or rectal and diagnosed at a later stage.
- Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood)Standard of care
- ShieldApproved
Background: Faecal immunochemical test (FIT). Also on OnCo: Symptoms and red flags · Early detection roadmap.
Cases by country
No country-level case numbers. This cancer is not mapped to a GLOBOCAN site.
One section per setting: the options named, what each is for, the trials behind them, the recorded trade-offs and the questions to ask.
Average-risk screening from age 45 (colonoscopy, faecal immunochemical test, stool DNA or blood test); earlier and more frequent colonoscopy for family history or a known syndrome; investigate rectal bleeding and iron deficiency promptly at any age.
Germline multigene testing for every patient; mismatch repair, RAS, BRAF and HER2 testing; fertility counselling before treatment.
As for colorectal and rectal cancer by stage: surgery, adjuvant FOLFOX or CAPOX for stage III, total neoadjuvant therapy or organ preservation for rectal tumours; no escalation on the basis of age alone.
Genotype-directed therapy as for all metastatic colorectal cancer: checkpoint blockade if mismatch-repair deficient, encorafenib-cetuximab for BRAF V600E, HER2 or KRAS G12C combinations, otherwise chemotherapy with bevacizumab or an anti-EGFR antibody by sidedness.
Structured exercise (CHALLENGE), long-term neuropathy and bowel function care, fertility and sexual health follow-up, financial and employment support.
Subtypes & biomarkers
top- Sporadic early-onset colorectal cancer (the large majority; mostly left colon and rectum, microsatellite-stable)
- Hereditary early-onset colorectal cancer (Lynch syndrome, familial adenomatous polyposis and other germline variants, about one in six)
- Early-onset rectal cancer (fertility, sexual function and stoma questions loom larger)
- Mismatch-repair deficient early-onset tumours (immunotherapy as in other dMMR disease)
- Multigene germline panel for every patient diagnosed under 50
- Mismatch repair / microsatellite status
- RAS, BRAF V600E and HER2 as for all colorectal cancer
- Colibactin (pks+ E. coli) mutational signature (research)
- Iron deficiency and rectal bleeding as presenting signs at any age
How often this target appears
- 2017Siegel and colleagues show a birth-cohort rise in colon and rectal cancer in young adults
- 2017Pearlman: about one in six patients under 50 carries a germline predisposition variant
- 2018American Cancer Society lowers the screening start age to 45
- 2021US Preventive Services Task Force recommends screening from 45
- 2025Colibactin mutational signature found enriched in early-onset tumours (Nature)
Dated changes read from the records linked to this cancer: approvals, regulatory steps, reported trials, guideline versions and milestones. Newest first; no date is inferred.
All 10 changes by month →- 2026-09-17This recordEarly-onset colorectal cancer (under 50)Facts on this page last checked
When this page itself was last checked or edited.
- 2025Trial resultCHALLENGE (CCTG CO.21)CHALLENGE (CCTG CO.21) reported
DFS HR 0.
- 2025MilestoneColorectal cancer screening (colonoscopy, FIT, stool DNA, blood)Colibactin mutational signature found enriched in early-onset tumours (Nature)
A milestone in how this cancer is treated.
- 2024Trial resultECLIPSE (Shield blood test)ECLIPSE (Shield blood test) reported
Sensitivity 83.
- 2022Trial resultNordICC (Nordic-European Initiative on Colorectal Cancer)NordICC (Nordic-European Initiative on Colorectal Cancer) reported
10-year colorectal cancer risk 0.
- 2021MilestoneColorectal cancer screening (colonoscopy, FIT, stool DNA, blood)US Preventive Services Task Force recommends screening from 45
A milestone in how this cancer is treated.
What is in development for Early-onset colorectal cancer (under 50), drawn from the whole corpus: 5 items. Drugs are grouped by the most advanced trial phase they have reached anywhere; approved treatments sit under standard of care. Technologies are the methods being tested for this cancer, trials are the studies recorded here, and ideas are proposals not yet in a trial.
Technologies being tested · 2
Ideas not yet in a trial · 3
Open problems and what is being done
The cause of the rise is unknown; no exposure has been proven.
Diagnostic delay in young adults with rectal bleeding remains long.
Whether screening should start at 45, 40 or by individual risk is unsettled outside the United States.
and how the field plans to fix it →What is being done about thisFinding cancer earlierAvailable now- Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood)Standard of care
- ShieldApproved
In trialsBackground: Faecal immunochemical test (FIT). Also on OnCo: Symptoms and red flags · Early detection roadmap.
Fertility, sexual function and financial toxicity are poorly measured in trials.
and how the field plans to fix it →What is being done about thisSide effects and quality of lifeAvailable now- BevacizumabApproved
- Exercise & lifestyle oncologyEstablished
In trialsNothing recorded yet.
Ideas and roadmapsNothing recorded yet.
Also on OnCo: Side effects by symptom · Immune-related side effects · Toxicity compare · Survivorship planner.
Trials
topTrials recruiting now
Country and place are remembered in this browser only. A postcode is sent to OpenStreetMap's Nominatim service to find coordinates when you press the button; nothing else leaves your device.
Landmark trials
Expert centres
topExpert centres
Toronto · cancer center | Canada | none recorded | 1 | 1,472 | 21,426 | none recorded | #9 |
Baltimore · cancer center | United States | 0 | 2,955 | 41,449 | #10 | ||
| Spain | none recorded | 0 | 966 | 23,221 | none recorded | #28 | |
Toronto · consortium | Canada | none recorded | 1 | 20 | 189 | none recorded | - |
Beijing · hospital | China | none recorded | 0 | 1,784 | 18,230 | - | |
Pittsburgh, PA · cancer center | United States | 0 | 1,078 | 21,539 | - | ||
L'Hospitalet de Llobregat · cancer center | Spain | 0 | 988 | 14,310 | - | ||
Oakland, CA · research institute Programme: Colorectal cancer screening outcomes | United States | none recorded | 0 | 908 | 10,296 | - | |
Rochester, NY · cancer center | United States | 0 | 861 | 12,212 | - | ||
Philadelphia, PA · cancer center | United States | 0 | 755 | 12,225 | - | ||
Philadelphia, PA · hospital | United States | none recorded | 0 | 695 | 9,931 | - | |
Nagaizumi, Shizuoka · cancer center | Japan | none recorded | 0 | 657 | 3,545 | - | |
London · research institute | United Kingdom | none recorded | 0 | 641 | 10,459 | none recorded | - |
Helsinki · cancer center | Finland | none recorded | 0 | 558 | 5,920 | - | |
Lund · hospital | Sweden | none recorded | 0 | 521 | 4,154 | - |
These are the things we can measure; they are not a ranking of quality. Each column is a field on the institution record or a count over what OnCo has linked; a centre that treats many patients with Early-onset colorectal cancer but is thinly recorded here will look small.
Not known: OnCo holds no case-volume or outcome figures for centres, so none are shown. Where a national audit or registry publishes them, the centre's page links to it. Default order: Newsweek rank, then trials for this cancer, then research output.
Questions to ask
topQuestions to ask your oncologist about Early-onset colorectal cancer
Newly diagnosed
- What is my exact diagnosis, stage, and grade, and which tests established them?Why: Everything else follows from an accurate stage and subtype.
- Which biomarkers have been tested on my tumour (for example Multigene germline panel for every patient diagnosed under 50, Mismatch repair / microsatellite status, RAS, BRAF V600E and HER2 as for all colorectal cancer, Colibactinmutational signature, Iron deficiency and rectal bleeding as presenting signs at any age), and what were the results?Why: These results decide eligibility for targeted therapy, immunotherapy, and trials.
- Which subtype is my cancer, and does that change the recommended treatment?Why: Recognised subtypes for this cancer include Sporadic early-onset colorectal cancer, Hereditary early-onset colorectal cancer, Early-onset rectal cancer.
- Is germline (inherited) genetic testing recommended for me or my family?Why: Inherited variants can change treatment and matter for relatives.
Screening and early diagnosis
- For my situation (screening and early diagnosis), which of the standard options do you recommend and why?Why: Guideline options include: Average-risk screening from age 45 (colonoscopy, faecal immunochemical test, stool DNA or blood test); earlier and more frequent colonoscopy for family history or a known syndrome; investigate rectal bleeding and iron deficiency promptly at any age.
- Am I a candidate for Shield, Cologuard, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Diagnosis and staging
- For my situation (diagnosis and staging), which of the standard options do you recommend and why?Why: Guideline options include: Germline multigene testing for every patient; mismatch repair, RAS, BRAF and HER2 testing; fertility counselling before treatment.
Localised disease
- For my situation (localised disease), which of the standard options do you recommend and why?Why: Guideline options include: As for colorectal and rectal cancer by stage: surgery, adjuvant FOLFOX or CAPOX for stage III, total neoadjuvant therapy or organ preservation for rectal tumours; no escalation on the basis of age alone.
- Am I a candidate for FOLFOX (5-FU, leucovorin, oxaliplatin), CAPOX (capecitabine, oxaliplatin), and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of RAPIDO apply to someone like me?Why: Trial populations differ from individual patients; ask how closely you match.
Metastatic disease
- For my situation (metastatic disease), which of the standard options do you recommend and why?Why: Guideline options include: Genotype-directed therapy as for all metastatic colorectal cancer: checkpoint blockade if mismatch-repair deficient, encorafenib-cetuximab for BRAF V600E, HER2 or KRAS G12C combinations, otherwise chemotherapy with bevacizumab or an anti-EGFR antibody by sidedness.
- Am I a candidate for Pembrolizumab, Encorafenib, Tucatinib or related drugs, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Survivorship
- For my situation (survivorship), which of the standard options do you recommend and why?Why: Guideline options include: Structured exercise (CHALLENGE), long-term neuropathy and bowel function care, fertility and sexual health follow-up, financial and employment support.
- How do the results of CHALLENGE (CCTG CO.21) apply to someone like me?Why: Trial populations differ from individual patients; ask how closely you match.
Any stage
- Are there clinical trials I could join, for example of Use a polygenic risk score to set when screening starts, Automatic germline testing for every cancer type where it changes care, Shield, Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood)?Why: Trials are how the next standard of care is set; asking early keeps options open.
- Would a second opinion at a high-volume centre change anything, and can you help arrange it?Why: Rare or high-stakes decisions benefit from a centre that treats many similar patients.
- What supportive care (symptom control, nutrition, exercise, mental health, financial help) is available from the start?Why: Supportive care improves quality of life and helps patients complete treatment.
- I read that “The cause of the rise is unknown; no exposure has been proven”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
- I read that “Diagnostic delay in young adults with rectal bleeding remains long”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
Newly diagnosed? Read the first 60 days with Early-onset colorectal cancer, then print the one-page appointment sheet with room for the answers.
Print this page for your appointment (your browser's print command). These prompts are for discussion; your clinical team knows your case.
Direct links plus the targets, companies, and technologies of this cancer's products.
technologies
17targets
6drugs
10companies
8pathways
1terms
7trials
4ideas
3people
2Latest papers
topQuery for this cancer: (TITLE:"Early-onset colorectal cancer" OR ABSTRACT:"Early-onset colorectal cancer" OR TITLE:"under 50" OR ABSTRACT:"under 50" OR TITLE:"Young-onset colorectal cancer" OR ABSTRACT:"Young-onset colorectal cancer" OR TITLE:"Colorectal cancer in adults under 50" OR ABSTRACT:"Colorectal cancer in adults under 50" OR TITLE:"Early-age-onset colorectal cancer" OR ABSTRACT:"Early-age-onset colorectal cancer" OR TITLE:"Bowel cancer in young adults" OR ABSTRACT:"Bowel cancer in young adults") AND (treatment OR therapy OR trial OR survival OR diagnosis). Results are unfiltered search hits about Early-onset colorectal cancer (under 50), not a curated reading list.
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