Small intestine cancer (small bowel adenocarcinoma)
Cancers of the small intestine are rare and often found late because the small bowel is hard to see and symptoms are vague. Surgery cures early disease, chemotherapy borrowed from bowel cancer helps after surgery and in advanced disease, and a large minority of tumours have a repair defect that makes them respond well to immunotherapy.
Overview
Small bowel adenocarcinoma (SBA) is the epithelial cancer of the duodenum, jejunum and ileum; the small intestine also gives rise to neuroendocrine tumours (the most common small bowel malignancy in some registries), gastrointestinal stromal tumours and lymphoma, each covered on their own pages. Risk factors for SBA are inflammatory and hereditary: Crohn's disease (ileal tumours), coeliac disease (jejunal tumours, often MSI-high), Lynch syndrome, familial adenomatous polyposis (duodenal and periampullary tumours) and Peutz-Jeghers syndrome. Molecularly, SBA sits between colorectal and gastric cancer: KRAS and TP53 mutations are common, APC mutation is less common than in colon cancer, and mismatch-repair deficiency is found in a larger share than in colorectal cancer, with a further subset carrying HER2 amplification or ERBB2 mutations.
Segmental resection with regional lymphadenectomy (pancreatoduodenectomy for duodenal tumours) is the curative treatment. Adjuvant chemotherapy has been extrapolated from colorectal cancer; the international BALLAD trial (NCT02502370) is the first randomised test of adjuvant fluoropyrimidine with or without oxaliplatin versus observation in stage I to III disease. For advanced disease, CAPOX or FOLFOX is first line; pembrolizumab is the first-line choice for MSI-high or mismatch-repair-deficient tumours, where response rates are high and durable. The NCCN small bowel adenocarcinoma guideline (2019 onwards) and the ASCO 2024 guideline now give the disease its own recommendations rather than a footnote in the colon guideline.
Open questions include the BALLAD result, second-line therapy beyond taxanes and irinotecan, HER2-directed therapy, and better ways to image the small bowel in high-risk patients (capsule endoscopy, MR enterography).
State of the art today
- Small bowel adenocarcinoma has its own NCCN (2019) and ASCO (2024) guidelines; it is no longer treated purely as a colon cancer analogue.
- Immunotherapy transformed the outlook for the MSI-high minority, which is larger than in colorectal cancer.
- BALLAD, an international academic trial, is answering whether adjuvant chemotherapy helps at all; results are awaited.
- Capsule endoscopy and MR enterography make the small bowel visible, allowing surveillance in Lynch, FAP, coeliac and Crohn's patients.
Where it starts and where it drains
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)Duodenal adenocarcinoma (most common site; FAP-associated) · Jejunal adenocarcinoma (coeliac-associated) · Ileal adenocarcinoma (Crohn's-associated) · MSI-high / mismatch-repair-deficient SBA · Small bowel neuroendocrine tumour (see neuroendocrine) · Small bowel GIST (see GIST) · Small bowel lymphoma (including enteropathy-associated T-cell lymphoma)
- Left colon and sigmoid
- Rectum
- Anal canal (HPV squamous)
- Appendix
- pericolic
- mesenteric root
- para-aortic
- mesorectal
- lateral pelvic and inguinal (anal)
Same organ: Colorectal cancer, Anal cancer (squamous cell carcinoma), Appendiceal cancer and pseudomyxoma peritonei
The small intestine is three quarters of the gut's length but hosts only a few percent of gastrointestinal cancers; adenocarcinoma, neuroendocrine tumours, lymphoma and GIST each make up a share (SEER).
- AI in radiologyEstablished
- cfDNA fragmentomicsEstablished
- Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood)Standard of care
- DNA methylation profilingEstablished
- HCC surveillance in cirrhosis (ultrasound + AFP)Standard of care
- High-risk pancreatic surveillance (CAPS / PRECEDE)Established
- A 28-day national pathway for people with a positive multi-cancer blood test
- A breath test to rule out cancer in people with vague symptoms
- A cancer blood test for older people arriving at A&E with unexplained symptoms
- A legislated, publicly reported 28-day standard from urgent referral to diagnosis
- A live national dashboard of stage at diagnosis as the scorecard for early detection
- A single 'cancer check at 60' appointment bundling all screening tests
Background: Alpha-fetoprotein (AFP), Barrett's oesophagus, CA 19-9, Early detection, Faecal immunochemical test (FIT). Also on OnCo: Symptoms and red flags · Early detection roadmap.
Where the cases are
No country-level case numbers. This cancer is not mapped to a GLOBOCAN site.
Segmental resection with en bloc lymphadenectomy; pancreatoduodenectomy for duodenal tumours not amenable to segmental resection.
Fluoropyrimidine with oxaliplatin (CAPOX or FOLFOX) for six months, extrapolated from colon cancer; BALLAD is the randomised test.
Pembrolizumab first line (tumour-agnostic approval; ZEBRA and KEYNOTE-158 cohorts).
CAPOX or FOLFOX first line; taxane- or irinotecan-based second line; HER2-directed therapy in trials; clinical trial enrolment encouraged.
Subtypes & biomarkers
top- Duodenal adenocarcinoma (most common site; FAP-associated)
- Jejunal adenocarcinoma (coeliac-associated)
- Ileal adenocarcinoma (Crohn's-associated)
- MSI-high / mismatch-repair-deficient SBA
- Small bowel neuroendocrine tumour (see neuroendocrine)
- Small bowel GIST (see GIST)
- Small bowel lymphoma (including enteropathy-associated T-cell lymphoma)
- MSI / mismatch repair (dMMR) status
- HER2 amplification or ERBB2 mutation
- KRAS, BRAF (rarely V600E), TP53
- Germline testing where Lynch, FAP or Peutz-Jeghers is suspected
- CEA and CA 19-9 for monitoring
- Coeliac serology and Crohn's history in the work-up
Target prevalence in this cancer
- 1746First description of duodenal carcinoma
Hamburger's case report.
- 2005Systematic profiling of SBA begins
Registry analyses show the distinct site distribution and association with Crohn's, coeliac and FAP.
- 2015Molecular landscape of SBA published
Schrock and colleagues (JAMA Oncol 2017) later show SBA is genomically distinct from colorectal and gastric cancer, with frequent dMMR and ERBB2 alterations.
- 2016BALLAD adjuvant trial opens
First randomised trial in resected small bowel adenocarcinoma (NCT02502370).
- 2017Pembrolizumab tumour-agnostic approval for MSI-high cancers
Small bowel adenocarcinoma is one of the eligible tumours.
- 2019NCCN publishes dedicated SBA guideline
- 2024ASCO guideline on small bowel adenocarcinoma
Open problems, and what is being done about each
Adjuvant chemotherapy benefit is unproven; BALLAD is the randomised answer.
Second-line therapy for MSS disease is weak; HER2 antibody-drug conjugates and trials in rare GI tumours are the route.
and how the field plans to fix it →What is being done about thisRare cancers and small trialsAvailable now- Comprehensive genomic profilingStandard of care
- AI trial matching & clinical decision supportEstablished
- Dinutuximab (ch14.18) / dinutuximab betaApproved
- Eflornithine (DFMO)Approved
- LarotrectinibApproved
- Limb-salvage surgery and endoprosthetic reconstructionStandard of care
In trials- ACTIONRecruiting
- COG AALL1731Positive
- COG ANBL0032Positive
- DeFiPositive
- Euro Ewing 2012Positive
- Functional (ex vivo) drug testingEmerging
Ideas and roadmaps- A digital second-opinion network answering community oncologists within 72 hours
- A DRUP-style protocol for off-label generic targeted drugs in rare tumours
- A funded expert second opinion for every new high-stakes or rare cancer diagnosis
- A global first-in-human network for academic cancer trials with single ethics review
- A global open trials operating system any hospital can plug into
- A live 'seats available' feed for trial slots, like airline inventory
Background: Basket, umbrella, and platform trials, Centralisation and high-volume centres, FNCLCC grade (soft-tissue sarcoma), Histotype-tailored therapy, INRG staging and risk groups. Also on OnCo: Find a trial · Expert centres.
Late diagnosis because the small bowel is hard to image; capsule endoscopy and MR enterography surveillance in high-risk groups is being formalised.
and how the field plans to fix it →What is being done about thisFinding cancer earlierAvailable now- AI in radiologyEstablished
- cfDNA fragmentomicsEstablished
- Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood)Standard of care
- DNA methylation profilingEstablished
- HCC surveillance in cirrhosis (ultrasound + AFP)Standard of care
- High-risk pancreatic surveillance (CAPS / PRECEDE)Established
In trialsIdeas and roadmaps- A 28-day national pathway for people with a positive multi-cancer blood test
- A breath test to rule out cancer in people with vague symptoms
- A cancer blood test for older people arriving at A&E with unexplained symptoms
- A legislated, publicly reported 28-day standard from urgent referral to diagnosis
- A live national dashboard of stage at diagnosis as the scorecard for early detection
- A single 'cancer check at 60' appointment bundling all screening tests
Background: Alpha-fetoprotein (AFP), Barrett's oesophagus, CA 19-9, Early detection, Faecal immunochemical test (FIT). Also on OnCo: Symptoms and red flags · Early detection roadmap.
Rarity fragments research; international registries and platform trials are the response.
and how the field plans to fix it →What is being done about thisRare cancers and small trialsAvailable now- Comprehensive genomic profilingStandard of care
- AI trial matching & clinical decision supportEstablished
- Dinutuximab (ch14.18) / dinutuximab betaApproved
- Eflornithine (DFMO)Approved
- LarotrectinibApproved
- Limb-salvage surgery and endoprosthetic reconstructionStandard of care
In trials- ACTIONRecruiting
- COG AALL1731Positive
- COG ANBL0032Positive
- DeFiPositive
- Euro Ewing 2012Positive
- Functional (ex vivo) drug testingEmerging
Ideas and roadmaps- A digital second-opinion network answering community oncologists within 72 hours
- A DRUP-style protocol for off-label generic targeted drugs in rare tumours
- A funded expert second opinion for every new high-stakes or rare cancer diagnosis
- A global first-in-human network for academic cancer trials with single ethics review
- A global open trials operating system any hospital can plug into
- A live 'seats available' feed for trial slots, like airline inventory
Background: Basket, umbrella, and platform trials, Centralisation and high-volume centres, FNCLCC grade (soft-tissue sarcoma), Histotype-tailored therapy, INRG staging and risk groups. Also on OnCo: Find a trial · Expert centres.
Trials
topRecruiting now (live from ClinicalTrials.gov)
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Expert centres
topCentres linked to this cancer in OnCo
- via Trastuzumab deruxtecan
- Johns Hopkins Hospital / Sidney Kimmel Comprehensive Cancer CenterBaltimore, USNewsweek oncology #10NCI comprehensivevia Pembrolizumab, Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)
- via Trastuzumab deruxtecan
- Alliance for Clinical Trials in OncologyChicago, IL, USvia Pembrolizumab
- GOG FoundationPhiladelphia, PA, USvia Pembrolizumab
- Institut Jules BordetBrussels, BEvia Pembrolizumab
- via Pembrolizumab
- National Cancer Center Hospital EastKashiwa, Chiba, JPvia Trastuzumab deruxtecan
- via Trastuzumab deruxtecan
Questions to ask
topQuestions to ask your oncologist about Small intestine 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 MSI / mismatch repairstatus, HER2 amplification or ERBB2 mutation, KRAS, BRAF, TP53, Germline testing where Lynch, FAP or Peutz-Jeghers is suspected, CEA and CA 19-9 for monitoring), 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 Duodenal adenocarcinoma, Jejunal adenocarcinoma, Ileal adenocarcinoma.
- Is germline (inherited) genetic testing recommended for me or my family?Why: Inherited variants can change treatment and matter for relatives.
Localised
- For my situation (localised), which of the standard options do you recommend and why?Why: Guideline options include: Segmental resection with en bloc lymphadenectomy; pancreatoduodenectomy for duodenal tumours not amenable to segmental resection.
Adjuvant (stage III; selected stage II)
- For my situation (adjuvant (stage iii; selected stage ii)), which of the standard options do you recommend and why?Why: Guideline options include: Fluoropyrimidine with oxaliplatin (CAPOX or FOLFOX) for six months, extrapolated from colon cancer; BALLAD is the randomised test.
- Am I a candidate for CAPOX (capecitabine, oxaliplatin), FOLFOX (5-FU, leucovorin, oxaliplatin), and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Advanced, MSI-high / dMMR
- For my situation (advanced, msi-high / dmmr), which of the standard options do you recommend and why?Why: Guideline options include: Pembrolizumab first line (tumour-agnostic approval; ZEBRA and KEYNOTE-158 cohorts).
- Am I a candidate for Pembrolizumab, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Advanced, MSS
- For my situation (advanced, mss), which of the standard options do you recommend and why?Why: Guideline options include: CAPOX or FOLFOX first line; taxane- or irinotecan-based second line; HER2-directed therapy in trials; clinical trial enrolment encouraged.
- Am I a candidate for CAPOX (capecitabine, oxaliplatin), FOLFOX (5-FU, leucovorin, oxaliplatin), FOLFIRI (5-FU, leucovorin, irinotecan) or related drugs, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Any stage
- Are there clinical trials I could join, for example of Pembrolizumab, Trastuzumab deruxtecan, Signatera?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 “Adjuvant chemotherapy benefit is unproven; BALLAD is the randomised answer”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
- I read that “Second-line therapy for MSS disease is weak; HER2 antibody-drug conjugates and trials in rare GI tumours are the route”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
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
10targets
3drugs
7companies
5pathways
3terms
6bottlenecks
3Latest papers
topQuery for this cancer: (TITLE:"Small intestine cancer" OR ABSTRACT:"Small intestine cancer" OR TITLE:"small bowel adenocarcinoma" OR ABSTRACT:"small bowel adenocarcinoma" OR TITLE:"Small bowel adenocarcinoma" OR ABSTRACT:"Small bowel adenocarcinoma" OR TITLE:"Duodenal cancer" OR ABSTRACT:"Duodenal cancer" OR TITLE:"Jejunal and ileal cancer" OR ABSTRACT:"Jejunal and ileal cancer" OR TITLE:"SBA" OR ABSTRACT:"SBA") AND (treatment OR therapy OR trial OR survival OR diagnosis). Results are unfiltered search hits about Small intestine cancer (small bowel adenocarcinoma), not a curated reading list.
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