{"entity":{"id":"small-bowel","kind":"cancer","name":"Small intestine cancer (small bowel adenocarcinoma)","aka":["Small bowel adenocarcinoma","Duodenal cancer","Jejunal and ileal cancer","SBA"],"tldr":"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.","summary":"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.\n\nSegmental 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.\n\nOpen 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).","asOf":"2026-09-10","wikipedia":"https://en.wikipedia.org/wiki/Small_intestine_cancer","links":[{"label":"NCI PDQ: small intestine cancer","url":"https://www.cancer.gov/types/small-intestine"},{"label":"ASCO guideline: small bowel adenocarcinoma (JCO 2024)","url":"https://www.asco.org/guidelines"},{"label":"NCCN: Small Bowel Adenocarcinoma","url":"https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1490"},{"label":"BALLAD trial (NCT02502370)","url":"https://clinicaltrials.gov/study/NCT02502370"},{"label":"SEER: small intestine cancer","url":"https://seer.cancer.gov/statfacts/html/smint.html"}],"tags":["nci-coverage","rare","gastrointestinal"],"related":["neuroendocrine","gist","colorectal","ampullary"],"cancers":[],"sections":[],"technologies":["cytotoxic-chemotherapy","checkpoint-inhibitor","endoscopy","mri","cgp","germline-testing"],"targets":["her2","kras","pd1"],"drugs":["capox","folfox","folfiri","pembrolizumab","paclitaxel","trastuzumab-deruxtecan"],"companies":[],"institutions":[],"pathways":["mismatch-repair-msi","ras-mapk","wnt"],"terms":["msi","lynch-syndrome","hereditary-cancer-syndromes","whipple","lymphadenectomy"],"trials":[],"people":[],"bottlenecks":["b-rare-cancers","b-trial-enrolment","b-early-detection"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"group":"gastrointestinal","burden":"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).","subtypes":["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)"],"biomarkers":["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"],"standardOfCare":[{"setting":"Localised","approach":"Segmental resection with en bloc lymphadenectomy; pancreatoduodenectomy for duodenal tumours not amenable to segmental resection.","refs":["whipple","lymphadenectomy"],"guideline":{"nccn":"Category 2A","version":"NCCN Guidelines: Small Bowel Adenocarcinoma","url":"https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1490"}},{"setting":"Adjuvant (stage III; selected stage II)","approach":"Fluoropyrimidine with oxaliplatin (CAPOX or FOLFOX) for six months, extrapolated from colon cancer; BALLAD is the randomised test.","refs":["capox","folfox","ballad"],"guideline":{"nccn":"Category 2A","version":"NCCN Guidelines: Small Bowel Adenocarcinoma; ASCO guideline 2024","url":"https://www.asco.org/guidelines"}},{"setting":"Advanced, MSI-high / dMMR","approach":"Pembrolizumab first line (tumour-agnostic approval; ZEBRA and KEYNOTE-158 cohorts).","refs":["pembrolizumab","msi","mismatch-repair-msi"],"guideline":{"nccn":"Category 2A (preferred)","version":"NCCN Guidelines: Small Bowel Adenocarcinoma"}},{"setting":"Advanced, MSS","approach":"CAPOX or FOLFOX first line; taxane- or irinotecan-based second line; HER2-directed therapy in trials; clinical trial enrolment encouraged.","refs":["capox","folfox","folfiri","paclitaxel"],"guideline":{"version":"NCCN Guidelines: Small Bowel Adenocarcinoma"}}],"stateOfArt":["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."],"history":[{"year":1746,"title":"First description of duodenal carcinoma","note":"Hamburger's case report.","refs":[]},{"year":2005,"title":"Systematic profiling of SBA begins","note":"Registry analyses show the distinct site distribution and association with Crohn's, coeliac and FAP.","refs":[]},{"year":2015,"title":"Molecular landscape of SBA published","note":"Schrock and colleagues (JAMA Oncol 2017) later show SBA is genomically distinct from colorectal and gastric cancer, with frequent dMMR and ERBB2 alterations.","refs":[]},{"year":2016,"title":"BALLAD adjuvant trial opens","note":"First randomised trial in resected small bowel adenocarcinoma (NCT02502370).","refs":[]},{"year":2017,"title":"Pembrolizumab tumour-agnostic approval for MSI-high cancers","note":"Small bowel adenocarcinoma is one of the eligible tumours.","refs":["pembrolizumab"]},{"year":2019,"title":"NCCN publishes dedicated SBA guideline","refs":[]},{"year":2024,"title":"ASCO guideline on small bowel adenocarcinoma","refs":["capox","folfox"]}],"pipeline":["pembrolizumab","trastuzumab-deruxtecan","signatera"],"openProblems":["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.","Late diagnosis because the small bowel is hard to image; capsule endoscopy and MR enterography surveillance in high-risk groups is being formalised.","Rarity fragments research; international registries and platform trials are the response."]},"route":"/cancers/small-bowel/","neighbours":{"cancer":[{"id":"advanced-small-bowel-adenocarcinoma","kind":"cancer","name":"Advanced and metastatic small bowel adenocarcinoma","route":"/cancers/advanced-small-bowel-adenocarcinoma/"},{"id":"ampullary","kind":"cancer","name":"Ampullary cancer (ampulla of Vater)","route":"/cancers/ampullary/"},{"id":"colorectal","kind":"cancer","name":"Colorectal cancer","route":"/cancers/colorectal/"},{"id":"enteropathy-associated-t-cell-lymphoma","kind":"cancer","name":"Enteropathy-associated T-cell lymphoma","route":"/cancers/enteropathy-associated-t-cell-lymphoma/"},{"id":"gist","kind":"cancer","name":"Gastrointestinal stromal tumour (GIST)","route":"/cancers/gist/"},{"id":"localised-small-bowel-adenocarcinoma","kind":"cancer","name":"Localised small bowel adenocarcinoma (stage I to III, resected)","route":"/cancers/localised-small-bowel-adenocarcinoma/"},{"id":"monomorphic-epitheliotropic-intestinal-t-cell-lymphoma","kind":"cancer","name":"Monomorphic epitheliotropic intestinal T-cell lymphoma","route":"/cancers/monomorphic-epitheliotropic-intestinal-t-cell-lymphoma/"},{"id":"neuroendocrine","kind":"cancer","name":"Neuroendocrine tumours","route":"/cancers/neuroendocrine/"}],"technology":[{"id":"capsule-endoscopy-systems","kind":"technology","name":"Capsule endoscopy (PillCam, EndoCapsule, CapsoCam)","route":"/technologies/capsule-endoscopy-systems/"},{"id":"cea-surveillance-colorectal","kind":"technology","name":"CEA surveillance after colorectal cancer surgery","route":"/technologies/cea-surveillance-colorectal/"},{"id":"cgp","kind":"technology","name":"Comprehensive genomic profiling","route":"/technologies/cgp/"},{"id":"cytotoxic-chemotherapy","kind":"technology","name":"Cytotoxic chemotherapy","route":"/technologies/cytotoxic-chemotherapy/"},{"id":"endoscopic-ultrasound-systems","kind":"technology","name":"Endoscopic ultrasound and EBUS systems","route":"/technologies/endoscopic-ultrasound-systems/"},{"id":"germline-testing","kind":"technology","name":"Germline (hereditary) testing","route":"/technologies/germline-testing/"},{"id":"checkpoint-inhibitor","kind":"technology","name":"Immune checkpoint inhibitors","route":"/technologies/checkpoint-inhibitor/"},{"id":"mri","kind":"technology","name":"MRI","route":"/technologies/mri/"}],"term":[{"id":"endoscopy","kind":"term","name":"Endoscopy (EGD, EUS, ERCP)","route":"/terms/endoscopy/"},{"id":"hereditary-cancer-syndromes","kind":"term","name":"Hereditary cancer syndromes","route":"/terms/hereditary-cancer-syndromes/"},{"id":"lymphadenectomy","kind":"term","name":"Lymphadenectomy (lymph node dissection)","route":"/terms/lymphadenectomy/"},{"id":"lynch-syndrome","kind":"term","name":"Lynch syndrome","route":"/terms/lynch-syndrome/"},{"id":"msi","kind":"term","name":"Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)","route":"/terms/msi/"},{"id":"whipple","kind":"term","name":"Whipple procedure (pancreaticoduodenectomy)","route":"/terms/whipple/"}],"target":[{"id":"cdkn1b","kind":"target","name":"CDKN1B","route":"/targets/cdkn1b/"},{"id":"her2","kind":"target","name":"HER2","route":"/targets/her2/"},{"id":"kras","kind":"target","name":"KRAS","route":"/targets/kras/"},{"id":"max","kind":"target","name":"MAX","route":"/targets/max/"},{"id":"nup214","kind":"target","name":"NUP214","route":"/targets/nup214/"},{"id":"pd1","kind":"target","name":"PD-1","route":"/targets/pd1/"},{"id":"ptprd","kind":"target","name":"PTPRD","route":"/targets/ptprd/"},{"id":"snx29","kind":"target","name":"SNX29","route":"/targets/snx29/"}],"drug":[{"id":"capox","kind":"drug","name":"CAPOX (capecitabine, oxaliplatin)","route":"/drugs/capox/"},{"id":"folfiri","kind":"drug","name":"FOLFIRI (5-FU, leucovorin, irinotecan)","route":"/drugs/folfiri/"},{"id":"folfox","kind":"drug","name":"FOLFOX (5-FU, leucovorin, oxaliplatin)","route":"/drugs/folfox/"},{"id":"paclitaxel","kind":"drug","name":"Paclitaxel / nab-paclitaxel","route":"/drugs/paclitaxel/"},{"id":"pembrolizumab","kind":"drug","name":"Pembrolizumab","route":"/drugs/pembrolizumab/"},{"id":"signatera","kind":"drug","name":"Signatera","route":"/drugs/signatera/"},{"id":"trastuzumab-deruxtecan","kind":"drug","name":"Trastuzumab deruxtecan","route":"/drugs/trastuzumab-deruxtecan/"}],"pathway":[{"id":"mismatch-repair-msi","kind":"pathway","name":"Mismatch repair & microsatellite instability","route":"/pathways/mismatch-repair-msi/"},{"id":"ras-mapk","kind":"pathway","name":"RAS / RAF / MEK / ERK (MAPK)","route":"/pathways/ras-mapk/"},{"id":"wnt","kind":"pathway","name":"Wnt / β-catenin","route":"/pathways/wnt/"}],"bottleneck":[{"id":"b-rare-cancers","kind":"bottleneck","name":"Rare and paediatric cancers without markets","route":"/bottlenecks/b-rare-cancers/"},{"id":"b-early-detection","kind":"bottleneck","name":"The hardest cancers are found late","route":"/bottlenecks/b-early-detection/"},{"id":"b-trial-enrolment","kind":"bottleneck","name":"Trials enrol too few, too slowly","route":"/bottlenecks/b-trial-enrolment/"}],"trial":[{"id":"ballad","kind":"trial","name":"BALLAD","route":"/trials/ballad/"}],"journal":[{"id":"journal-of-gastrointestinal-cancer","kind":"journal","name":"Journal of gastrointestinal cancer","route":"/journals/journal-of-gastrointestinal-cancer/"}]}}