Stomach Cancer

Mucosa

Inner glandular lining in contact with food

Very early cancer in this lining may be suitable for endoscopic removal if its size and other features suggest a low risk of spread.

Submucosa

Support layer containing vessels and lymph channels

Cancer growing into this layer has a greater risk of spreading to lymph nodes; surgery is usually needed.

Muscularis propria

Thick muscle that churns food

Cancer reaching the muscle layer generally needs a combination of treatments.

Subserosa and serosa

Outer supporting tissue and surface covering

Cancer reaching these outer layers has a greater risk of spreading to the abdominal lining or nearby organs.

Adenocarcinoma — intestinal type

The cancer cells often form glands. It may develop after long-term inflammation of the stomach lining (gastritis), thinning of the lining (atrophy), and changes that make the lining resemble bowel tissue (intestinal metaplasia).

Adenocarcinoma — diffuse or signet-ring type

Cancer cells can spread through the stomach wall without forming a clear lump. They may be less visible on PET-CT. The team also assesses the abdominal lining and whether an inherited change in the CDH1 gene could be relevant.

Gastro-oesophageal junction adenocarcinoma

The gastro-oesophageal junction (GEJ) is where the food pipe meets the stomach. Cancers near this junction may follow a GEJ or oesophageal treatment plan. A multidisciplinary team (MDT), a group of specialists who plan care together, will identify where the tumour began.

GIST

A tumour arising from cells in the digestive-tract wall. Many have changes in the KIT or PDGFRA genes. Surgery and targeted medicines differ from treatment for adenocarcinoma.

Gastric lymphoma

A cancer of immune cells. Treatment may include treating Helicobacter pylori (H. pylori), a bacterium that can infect the stomach, or chemotherapy, antibody medicines or radiotherapy. Stomach removal is uncommon.

Neuroendocrine neoplasm

This tumour follows a separate treatment plan. The grade, Ki-67 result (a measure of how many cells are dividing) and whether the tumour makes hormones help guide care.

H. pylori infection

Can cause long-term inflammation, thinning of the stomach lining and cancer away from the stomach entrance.

Have testing and treatment when advised, followed by a test to check that the infection has cleared.

Tobacco

Smoking raises risk and also worsens surgical and cardiovascular outcomes.

Stopping helps at any stage; ask for medication and behavioural support.

Food and salt

High intake of salt-preserved or smoked foods is associated with risk; fruit and vegetables are protective dietary patterns.

Use refrigeration, reduce very salty preserved foods and avoid extreme diets.

Previous stomach disease or surgery

Risk can be higher with thinning or abnormal changes in the stomach lining, pernicious anaemia (vitamin B12 deficiency caused by poor absorption), some stomach polyps, or a stomach remnant many years after surgery.

Follow a specialist surveillance plan when one is recommended.

Family or inherited predisposition

A small proportion relate to inherited changes in the CDH1 or CTNNA1 genes, Lynch syndrome, or other inherited conditions.

A genetic counsellor can assess your family history and help choose and interpret a suitable test.

Hereditary diffuse gastric cancer

Usually involves CDH1 and sometimes CTNNA1. Expert surveillance and, for selected proven carriers, risk-reducing total gastrectomy may be discussed.

Lynch syndrome

Inherited changes in genes that repair genetic material increase bowel and several other cancer risks. Results help guide screening for the person and their relatives.

Other rare syndromes

Familial adenomatous polyposis (FAP), gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), Peutz–Jeghers syndrome and juvenile polyposis may require regular checks of the upper digestive tract.

Contrast CT

Main map of stomach wall thickening, lymph nodes, liver, lungs and peritoneum.

Small peritoneal deposits and microscopic disease may be missed.

Endoscopic ultrasound

Estimates depth and nearby nodes; especially helpful when considering endoscopic resection.

Less useful if the scope cannot pass or inflammation distorts layers.

Fluorodeoxyglucose (FDG) PET-CT

Uses a small amount of radioactive sugar (FDG) to help find spread to distant sites that other tests may miss.

Diffuse, signet-ring and mucinous cancers can show low uptake; not a substitute for quality CT.

MRI

Problem-solving for liver lesions, pelvis or when CT contrast is unsuitable.

Not routinely required for every patient.

Staging laparoscopy + washings

Lets the surgeon inspect the abdominal lining and take samples of small deposits. Fluid used to wash the area is tested for cancer cells.

A procedure under anaesthesia; negative findings cannot guarantee that microscopic disease is absent.

Histology

Usually adenocarcinoma; intestinal, diffuse, mixed, poorly cohesive or signet-ring features may be described.

Grade/differentiation

How closely cancer resembles normal glands. Poorly differentiated cells usually behave more aggressively, but stage remains crucial.

Tumour depth after surgery (pT)

Deepest layer or nearby structure invaded by the tumour.

Lymph-node findings after surgery (pN)

Number examined and number containing cancer. A D2 operation and adequate node count improve staging quality.

Margins (R status)

R0 means all visible cancer is removed and the cut edges are clear under the microscope. R1 means cancer cells are found at a cut edge; R2 means visible cancer remains.

Lymphovascular/perineural invasion

Cancer seen in lymph/blood vessels or around nerves; these are recurrence-risk features.

Treatment response

After pre-operative therapy, the pathologist estimates how much viable tumour remains.

Human epidermal growth factor receptor 2 (HER2)

Immunohistochemistry (IHC) stains tissue to measure HER2 protein. Scores are 0, 1+, 2+ or 3+. A 2+ result needs in situ hybridisation (ISH), a test for extra copies of the HER2 gene. HER2-positive means IHC 3+, or IHC 2+ with a positive ISH result.

HER2-positive disease can receive trastuzumab-based first-line therapy and, after trastuzumab, trastuzumab deruxtecan in suitable patients.

Programmed death-ligand 1 (PD-L1)

Combined positive score (CPS): a measure of PD-L1 staining in cancer cells and nearby immune cells.

Helps assess the likely benefit from immunotherapy that blocks programmed cell death protein 1 (PD-1), a signal that can limit the immune response. The required result depends on the medicine and treatment setting.

Mismatch repair (MMR) / microsatellite instability (MSI)

These tests assess how well cells repair errors in genetic material. Results may show proficient repair (pMMR) and microsatellite stability (MSS), or deficient repair (dMMR) and high microsatellite instability (MSI-H).

MSI-H/dMMR cancers may respond particularly well to immunotherapy. Results can also suggest Lynch syndrome. Testing matters in early as well as advanced disease.

Claudin 18.2 (CLDN18.2)

A validated IHC tissue test measures this protein on cancer cells. The result must meet the treatment’s required amount and strength of staining.

Positive HER2-negative advanced cancers may receive zolbetuximab with platinum/fluoropyrimidine chemotherapy where available.

Broad genomic testing

Next-generation sequencing (NGS) tests many genes at once, using tumour tissue or sometimes blood.

May find rare fusions involving neurotrophic tyrosine receptor kinase (NTRK) genes, a high tumour mutational burden (TMB, the number of gene changes in the cancer), or clinical trial options. A negative blood test does not rule out a change in the tumour.

Very early cancer, including selected T1a

Endoscopic submucosal dissection, then careful pathology review.

Is the cancer limited to the lining, completely removed and unlikely to have spread to lymph nodes?

Cancer that can be removed

Stomach surgery with D2 lymph-node removal. Treatment before and after surgery is usually offered when cancer reaches the muscle layer or deeper, or involves lymph nodes.

Can surgery remove all the cancer with clear margins? Is chemotherapy suitable? Have laparoscopy and washings been completed when indicated?

Grown nearby / surgery may be difficult

Systemic therapy first; reassess response and resectability. Radiotherapy is selective.

Can surgery safely remove the cancer? Is there hidden spread on the abdominal lining, or growth that makes surgery unlikely to help?

Distant spread / cancer cells in washings

Biomarker-led systemic treatment plus symptom control. Surgery is rarely curative.

Which biomarker results guide the first treatment? Do any symptoms need a procedure for prompt relief?

Open

A larger abdominal incision. May be preferred for bulky disease, adjacent-organ involvement or when safety requires.

Laparoscopic

Keyhole surgery through small incisions. Appropriate for selected patients in experienced hands.

Robotic

Keyhole surgery using robotic instruments controlled by the surgeon. The choice depends on the cancer, your health and the planned operation.

Distal subtotal gastrectomy

The lower stomach, nearby lymph nodes and the omentum (a fatty apron of tissue in the abdomen). Nearby tissue may also be removed if involved.

The remaining stomach is joined to duodenum or jejunum, depending on the operation.

Total gastrectomy

The whole stomach, omentum and nearby lymph nodes. A short section of food pipe or part of a neighbouring organ is removed only when needed.

The oesophagus is joined to a Roux limb of jejunum. Bile and pancreatic juices meet food further downstream.

Proximal resection

The upper stomach in selected patients, with the lymph nodes and other tissues needed for the cancer operation.

The way the digestive tract is rejoined varies. The team considers eating and reflux (backflow into the food pipe). Many upper-stomach cancers need total gastrectomy or a GEJ treatment plan.

First 24–48 hours

Monitoring, pain relief, clot prevention, breathing exercises, tubes/drains as needed and early sitting/walking.

Tell the team if pain prevents deep breathing or movement.

Eating restarts

Small sips and then staged textures, or tube feeding if planned. Timing varies by surgeon and recovery.

Follow the dietitian’s plan; do not force large portions.

Hospital discharge

You should have wound advice, medicines, eating plan, red flags, pathology appointment and contact numbers.

Arrange support, transport and help with meals.

First 6–12 weeks

Fatigue, reduced capacity and weight change are common. Food tolerance evolves.

Frequent protein-rich intake, walking, strength recovery and scheduled review.

Long term

B12, iron, folate, calcium/vitamin D and bone health may need monitoring and replacement.

Keep lifelong nutrition follow-up after total gastrectomy.

Before surgery

Usually 4 cycles of FLOT: fluorouracil, leucovorin, oxaliplatin and docetaxel. Each cycle includes treatment and a recovery period. If this combination is unsuitable, the team may choose two chemotherapy drugs: oxaliplatin with a fluoropyrimidine such as fluorouracil or capecitabine.

Treat cancer cells too small to see, assess the cancer’s response and improve the chance of removing it completely.

Restage

Clinical review and CT; repeat laparoscopy in selected high-risk or suspicious situations.

Confirm no progression that would make gastrectomy unhelpful.

Surgery

Gastrectomy with D2 node dissection at an experienced centre.

Remove visible local and regional disease with clear margins.

After surgery

Resume the planned chemotherapy when recovery permits: continue FLOT if it was given before surgery, with durvalumab if already included in the treatment plan. Doses and the number of cycles may need adjustment.

Complete the planned drug treatment while monitoring nutrition, nerve symptoms such as tingling or numbness (neuropathy), blood counts and daily activities.

Adequate D2 resection, stage II–III

Adjuvant chemotherapy (treatment after surgery) with CAPOX (capecitabine and oxaliplatin) or FOLFOX (fluorouracil, leucovorin and oxaliplatin) can be considered if chemotherapy was not given before surgery. The choice depends on the pathology results, recovery and overall fitness.

Less-than-D2 nodal surgery or high local-risk features

Chemoradiotherapy (chemotherapy given with radiotherapy) after surgery may be discussed, particularly if no treatment was given before surgery.

Microscopically involved margin (R1)

Expert pathology confirmation, surgical review and consideration of chemoradiotherapy/systemic therapy. Re-operation is selective.

Very early, low-risk pathology

Surgery alone may be enough; confirm stage, margins and node assessment.

Poor recovery or frailty

A lower dose, simpler treatment or monitoring without further treatment may be safer, depending on recovery and overall health.

HER2-positive + PD-L1 CPS ≥1

Trastuzumab + platinum/fluoropyrimidine chemotherapy + pembrolizumab.

Check heart function and monitor immune-related and chemotherapy side effects.

HER2-positive + CPS <1

Trastuzumab + platinum/fluoropyrimidine chemotherapy remains a core option.

Pembrolizumab in this setting requires PD-L1 CPS ≥1.

HER2-negative, PD-L1 positive

Chemotherapy + immunotherapy

For adults with HER2-negative stomach or GEJ adenocarcinoma that cannot be removed by surgery or has spread, chemotherapy plus immunotherapy can be considered when PD-L1 CPS is at least 1. Benefit is generally more likely at higher PD-L1 scores.

The exact PD-L1 test and threshold depend on the medicine. Your doctor will also consider your general health and the chemotherapy combination. Both chemotherapy and immune-related side effects are possible; tell the team about autoimmune illness or an organ transplant.

HER2-negative, CLDN18.2 positive

Zolbetuximab with modified FOLFOX6 (mFOLFOX6, a schedule of the FOLFOX combination) or CAPOX, where available.

For adults with HER2-negative stomach or GEJ adenocarcinoma that cannot be removed or has spread. A validated tissue test must show CLDN18.2 positivity, with moderate-to-strong staining in at least 75% of cancer cells.

Nausea and vomiting can be pronounced, especially early. The team plans anti-sickness medicines and monitors appetite and reactions during the infusion.

MSI-H/dMMR

Immunotherapy is an important option. Some selected patients may receive it without intensive chemotherapy, depending on the treatment setting and previous treatment.

The team checks the exact medicine, previous-treatment requirements and whether assessment for Lynch syndrome is needed.

No suitable biomarker target or too frail for intensive treatment

Two-drug chemotherapy, an adjusted combination, a single medicine or symptom-focused care, depending on general health.

More treatment is not always better; reassess goals frequently.

Trastuzumab

Baseline and periodic heart function; infusion reaction; symptoms of heart failure such as breathlessness, swelling or rapid weight gain.

Pembrolizumab

The immune system can inflame healthy organs, including the lungs, bowel, liver, skin, kidneys and hormone-producing glands. These effects can occur even after treatment stops.

Platinum/fluoropyrimidine

Monitor blood counts, infection, nausea, diarrhoea, mouth soreness, painful redness of the hands or feet (hand-foot syndrome), kidney function, and nerve symptoms or cold sensitivity with oxaliplatin.

Every cycle

Symptoms, food and fluid intake, weight, daily activities, nerve symptoms, infection, bowel changes, bleeding and other side effects.

Blood tests

Blood counts, kidney and liver function, and blood salts. Immunotherapy also needs thyroid and other hormone checks. If ramucirumab is used later, blood pressure and protein in the urine are monitored.

Imaging

Usually CT after a defined number of cycles or sooner if symptoms worsen. Compare the same target lesions and sites.

Tumour markers

Carcinoembryonic antigen (CEA) or carbohydrate antigen 19-9 (CA 19-9) blood levels may help track changes if they were raised before treatment. They cannot replace scans and clinical assessment.

Goals

Is treatment shrinking cancer, stabilising it, relieving symptoms and preserving acceptable life quality?

Paclitaxel + ramucirumab

A common second treatment for someone well enough to receive it after fluoropyrimidine and platinum chemotherapy.

Nerve symptoms, low blood counts, bleeding, blood clots, high blood pressure, protein in the urine and slower wound healing.

Ramucirumab alone

When combination chemotherapy is unsuitable but treatment that blocks cancer-related blood-vessel growth remains an option.

Bleeding, clots, high blood pressure, protein in the urine and wound-healing problems remain concerns. Benefit may be smaller than with the combination.

Irinotecan or FOLFIRI (fluorouracil, leucovorin and irinotecan)

An alternative second chemotherapy treatment, particularly if nerve symptoms limit taxane drugs such as paclitaxel.

Diarrhoea, neutropenia (low infection-fighting white blood cells) and fatigue.

Trastuzumab deruxtecan

HER2-positive disease after trastuzumab-based therapy.

Interstitial lung disease, nausea, low counts; reassess HER2 when possible.

Immunotherapy

May suit MSI-H/dMMR cancers or another qualifying biomarker-based use that applies across different cancer types (a tumour-agnostic indication).

Immune-related side effects and the time needed for treatment to work; suitability varies between patients.

Trifluridine/tipiracil

For adults with metastatic stomach or GEJ adenocarcinoma after at least two previous treatment courses. Earlier treatment must include a fluoropyrimidine, a platinum, a taxane or irinotecan, and HER2-targeted treatment when appropriate.

Low blood counts, infection and fatigue. Take the tablets exactly according to the prescribed schedule.

MSI-H/dMMR

Suggests that PD-1 immunotherapy may help; also prompts assessment for Lynch syndrome.

NTRK fusion

Rare; may allow an NTRK inhibitor under a tumour-agnostic indication.

High tumour mutational burden

May allow immunotherapy after previous treatment when the test result and other eligibility requirements are met. Your team interprets it in the context of this cancer.

Blocked stomach outlet

A stent (a tube placed through an endoscope to hold the passage open), surgery to bypass the blockage, a tube to drain trapped contents, or cancer treatment in selected patients.

Choose according to expected duration of benefit, fitness and ability to eat.

Bleeding

Treatment through an endoscope, a blood transfusion or iron, radiotherapy, a procedure to block a bleeding blood vessel (embolisation), or surgery in selected emergencies.

Recurrent slow bleeding may first appear as fatigue or anaemia.

Swallowing difficulty at cardia/GEJ

Stent, radiotherapy or systemic treatment; nutrition access may be required.

A stent can relieve symptoms quickly but may cause reflux, pain or move out of position.

Ascites

Drainage, medicines that increase urine output in selected patients, other procedures for symptoms, and cancer treatment.

Repeated drainage can worsen protein loss; coordinate nutrition and fluid care.

Pain or nausea

Pain relief, anti-sickness medicines, acid-reducing medicines, steroids or procedures targeting pain nerves, depending on the cause.

Treat the mechanism—obstruction, constipation, medicines, infection or tumour—not only the symptom.

Protein and energy

Use small frequent meals/snacks; add eggs, dairy/curd, pulses, fish, chicken, nut pastes or prescribed supplements according to tolerance.

Hydration

Sip regularly between meals; use oral rehydration when diarrhoea/vomiting requires it and medical advice supports it.

Symptoms

Treat nausea, constipation, reflux, pain, oral thrush and obstruction promptly; they are medical barriers to eating.

Feeding access

A tube into the small bowel, passed through the nose or placed directly, can provide nutrition when eating is not enough. Nutrition through a vein is used only in selected situations.

Activity

Walking and resistance exercise, adapted to ability, help preserve muscle and function.

Early fullness and weight loss

Try 6–8 small meals or snacks, include protein and add energy-rich foods as advised. Drink mainly between meals if fluids fill you up. Marked or persistent symptoms need assessment for blockage or poor digestion, including a shortage of pancreatic enzymes.

Early dumping (10–30 minutes after eating)

Food moving quickly into the bowel may cause cramps, diarrhoea, sweating or dizziness. Smaller meals, fewer sugary foods or drinks, and fluids mainly between meals may help. Include protein, fat and slower-digesting carbohydrates.

Late dumping (1–3 hours after eating)

Low blood sugar may cause shaking, sweating, hunger or faintness. Try smaller balanced meals. Persistent symptoms need review; blood-sugar monitoring or medicines may help.

Reflux or bile reflux

Remain upright after eating, use smaller evening meals and take prescribed medicines; persistent symptoms need review of anatomy and narrowing.

Diarrhoea or pale, greasy stools

The team checks for infection, medicine effects, dumping, excess bile acids in the bowel or too few pancreatic digestive enzymes. Treatment depends on the cause.

Vitamins and minerals

Lifelong vitamin B12 replacement after total gastrectomy; monitor iron, folate, vitamin D, calcium and bone health. Replace documented deficits.