Advanced and metastatic small bowel adenocarcinoma: the decisions you may face
5 treatment settings, 3 with more than one named option. Each section lays out the options the standard of care names, what each is for, the trials behind them with their recorded results, the side effects and cautions on record, and questions to ask. Built from the cancer page's standard-of-care rows; nothing here is advice for your case.
First line, mismatch-repair proficient
CAPOX or FOLFOX, with bevacizumab considered; taxane-based regimens as an alternative.
CAPOX pairs the oral fluoropyrimidine capecitabine with intravenous oxaliplatin as a pill-based alternative to FOLFOX. For low-risk stage III colon cancer three months after surgery works as well as six and halves nerve damage; it is also standard in gastric cancer, with hand-foot syndrome as its price.
FOLFOX is the workhorse chemotherapy combination for bowel cancer, used after surgery to cure and in advanced disease as the backbone that targeted drugs are added to.
Bevacizumab is a humanised antibody that soaks up VEGF-A, the signal tumours use to grow new blood vessels. Approved in 2004, it partners chemotherapy in colorectal, ovarian, cervical, lung, kidney and liver cancer and glioblastoma, and adds to trifluridine/tipiracil in late-line bowel cancer; hypertension, protein in the urine and bleeding are its characteristic side effects.
A microtubule poison discovered in the Pacific yew tree, among the most used chemotherapies in breast, lung, and ovarian cancer.
Cytotoxic chemotherapy drugs (platinums, antimetabolites, microtubule agents and topoisomerase inhibitors) kill rapidly dividing cells by damaging DNA or the mitotic spindle. They still cure testicular cancer, lymphoma and leukaemia, and they are the warhead inside antibody-drug conjugates, but a narrow margin between effective and toxic doses is their limitation.
- Curative in several cancers
- Cheap, generic
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
- Narrow therapeutic index
- Resistance via efflux pumps and DNA repair
- Between CAPOX (capecitabine, oxaliplatin), FOLFOX (5-FU, leucovorin, oxaliplatin), Bevacizumab and the other options, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Small Bowel Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (first line, mismatch-repair proficient), which of the standard options do you recommend and why?Why: Guideline options include: CAPOX or FOLFOX, with bevacizumab considered; taxane-based regimens as an alternative.
- Am I a candidate for CAPOX (capecitabine, oxaliplatin), FOLFOX (5-FU, leucovorin, oxaliplatin), Bevacizumab or related drugs, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Add these to your appointment list, or take the full question set for this cancer.
First line, mismatch-repair deficient
Pembrolizumab (tumour-agnostic approval); nivolumab with ipilimumab as an alternative.
Pembrolizumab is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.
Nivolumab was the second PD-1 blocker and is often combined with ipilimumab. Long-term data show about half of advanced melanoma patients alive at 10 years on the combination.
Immune checkpoint inhibitors are antibodies against CTLA-4, PD-1 or PD-L1 that release the brakes on T cells so they attack the cancer. They are approved in more than 20 tumour types and produce lasting, sometimes curative responses that chemotherapy rarely does, but most patients do not respond and autoimmune side effects are the cost.
- Durable, sometimes curative responses
- Broad applicability
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Hypothyroidism (immune-mediated) · Pooled monotherapy data, >2,800 patients | 8% | - |
| Pneumonitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 3.4% | - |
| Colitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 1.7% | - |
| Hepatitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 0.7% | - |
- No pharmacokinetic interactions expected (antibody). See the irAE guide for toxicity management.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Colitis with ipilimumab (1+3 mg/kg) · Monotherapy pooled unless stated | 25% | 14.4% |
| Hepatitis with ipilimumab · Monotherapy pooled unless stated | 15% | 13.4% |
| Colitis · Monotherapy pooled unless stated | 2.9% | 1.7% |
| Hepatitis · Monotherapy pooled unless stated | 1.8% | 1.5% |
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
- Most patients do not respond
- Autoimmune toxicity
- Biomarkers are imperfect
- Between Pembrolizumab, Nivolumab and Immune checkpoint inhibitors, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- Which side effects of Pembrolizumab or Nivolumab are most likely for me, which are reversible, and which would make us stop?Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Small Bowel Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (first line, mismatch-repair deficient), which of the standard options do you recommend and why?Why: Guideline options include: Pembrolizumab (tumour-agnostic approval); nivolumab with ipilimumab as an alternative.
- Am I a candidate for Pembrolizumab, Nivolumab, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Add these to your appointment list, or take the full question set for this cancer.
Second line
FOLFIRI or a taxane; pembrolizumab if mismatch-repair deficient and not yet given; trastuzumab-based therapy or trastuzumab deruxtecan for HER2-positive tumours.
FOLFIRI is the other backbone bowel-cancer chemotherapy, swapping oxaliplatin for irinotecan. Used first or second line and, since 2026, with the BRAF combination.
A microtubule poison discovered in the Pacific yew tree, among the most used chemotherapies in breast, lung, and ovarian cancer.
Pembrolizumab is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.
Trastuzumab deruxtecan (Enhertu) is the most successful ADC ever. It redefined HER2 by working in tumours with only tiny amounts of the protein, and in 2026 moved into early-stage breast cancer.
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Hypothyroidism (immune-mediated) · Pooled monotherapy data, >2,800 patients | 8% | - |
| Pneumonitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 3.4% | - |
| Colitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 1.7% | - |
| Hepatitis (immune-mediated) · Pooled monotherapy data, >2,800 patients | 0.7% | - |
- No pharmacokinetic interactions expected (antibody). See the irAE guide for toxicity management.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Neutropenia · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 18% |
| Nausea · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 7% |
| Anaemia · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 7% |
| Fatigue · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 6% |
- Interstitial lung disease in 10-15%: hold for any respiratory symptom and image; permanently discontinue for grade 2 or above. Moderately emetogenic: three-drug prophylaxis.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
- Between FOLFIRI (5-FU, leucovorin, irinotecan), Paclitaxel / nab-paclitaxel, Pembrolizumab and the other options, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- Which side effects of Pembrolizumab or Trastuzumab deruxtecan are most likely for me, which are reversible, and which would make us stop?Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Small Bowel Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (second line), which of the standard options do you recommend and why?Why: Guideline options include: FOLFIRI or a taxane; pembrolizumab if mismatch-repair deficient and not yet given; trastuzumab-based therapy or trastuzumab deruxtecan for HER2-positive tumours.
- Am I a candidate for FOLFIRI (5-FU, leucovorin, irinotecan), Paclitaxel / nab-paclitaxel, Pembrolizumab or related drugs, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Add these to your appointment list, or take the full question set for this cancer.
Limited metastases
Resection of liver metastases or cytoreductive surgery with HIPEC for limited peritoneal disease in selected patients.
Washing the abdominal cavity with heated chemotherapy during surgery to kill microscopic peritoneal deposits.
- High local concentration
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
- Morbidity, centre expertise
- Mixed trial results
- Is HIPEC / PIPAC (intraperitoneal chemotherapy) the only reasonable path for me, or is there a trial, a different sequence or a wait-and-see option?Why: A single standard does not mean a single choice; timing and trials are decisions too.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Small Bowel Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (limited metastases), which of the standard options do you recommend and why?Why: Guideline options include: Resection of liver metastases or cytoreductive surgery with HIPEC for limited peritoneal disease in selected patients.
Add these to your appointment list, or take the full question set for this cancer.
All patients
Comprehensive genomic profiling to find HER2, mismatch repair deficiency and rare actionable alterations; referral to trials.
Sequencing hundreds of cancer genes at once from a biopsy to find the mutations a drug can target.
- One test, all actionable alterations
- Trial matching
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
- Tissue quantity
- VUS interpretation
- 2-3 week turnaround
- Is Comprehensive genomic profiling the only reasonable path for me, or is there a trial, a different sequence or a wait-and-see option?Why: A single standard does not mean a single choice; timing and trials are decisions too.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- Does your recommendation follow the current guideline (NCCN Guidelines: Small Bowel Adenocarcinoma), and if it departs from it, why?Why: Departures from guidelines are sometimes right for an individual; they should be explained.
- For my situation (all patients), which of the standard options do you recommend and why?Why: Guideline options include: Comprehensive genomic profiling to find HER2, mismatch repair deficiency and rare actionable alterations; referral to trials.
Add these to your appointment list, or take the full question set for this cancer.