The first 60 days: Gastric & gastro-oesophageal junction cancer
A cancer with three new targets in five years: Claudin 18.2, FGFR2b, and HER2 with new ADCs, plus immunotherapy in first line. Below, week by week, is what OnCo's record of Gastric & gastro-oesophageal junction cancer says about the first two months: the order is typical, the timing is yours to ask about. Sections appear only where the record has something to say. Orientation, not medical advice.
What happens now
Staging tests establish exactly what and where the cancer is. Everything else follows from the answers.
Ask which of these were tested and what the results were; see the report reader for what each value means.
These specialties appear in the standard of care for this cancer. In most centres they meet weekly as a tumour board to agree each plan; you can ask when yours was discussed and what was decided.
- PathologistNamed in the standard of care for: Advanced first line, Prevention and screening, Advanced, HER2-negative, PD-L1 CPS ≥5 (or ≥1), first line, Advanced, CLDN18.2-positive (≥75%), HER2-negative, first line and 1 more.
- SurgeonNamed in the standard of care for: Localised, Prevention and screening, Early (T1a) disease, Resectable stage II-III (Western) and 2 more.
- Medical oncologistNamed in the standard of care for: Localised, Advanced first line, Later lines, Resectable stage II-III (Western) and 9 more.
- Transplant and cell therapy teamNamed in the standard of care for: Later lines, Second line, HER2-negative.
- Palliative and supportive care teamNamed in the standard of care for: Peritoneal metastases.
A second opinion from a centre that treats many similar cases is normal, not rude; the standard of care tells you what to compare it against.
Each row is a setting from the standard of care, in the order it usually arises. Not all will apply to you; your stage and biomarkers decide which do. The guideline grade, where recorded, says how strong the evidence is.
H. pylori eradication reduces incidence; endoscopic screening programmes in Japan and Korea (biennial from age 40-50) detect most cancers at a curable stage. No population screening in the West. Prophylactic total gastrectomy for germline CDH1 carriers.
Perioperative FLOT ± durvalumab; D2 gastrectomy.
Endoscopic submucosal dissection for well-differentiated mucosal tumours ≤2 cm without ulceration (expanded criteria in Japan); otherwise gastrectomy.
Perioperative FLOT + durvalumab (MATTERHORN: OS HR 0.78, pCR 19%) with D2 gastrectomy; FOLFOX/CAPOX perioperatively for patients unfit for docetaxel.
D2 gastrectomy then adjuvant S-1 (ACTS-GC) or CAPOX (CLASSIC) for 6-12 months; neoadjuvant approaches increasingly adopted.
Chemotherapy + PD-1 ± trastuzumab ± zolbetuximab by biomarker.
Trastuzumab + fluoropyrimidine/platinum + pembrolizumab (KEYNOTE-811, PD-L1 CPS ≥1); zanidatamab + chemotherapy ± tislelizumab after HERIZON-GEA-01 (PFS 12.4 vs 8.1 months; sBLA 2026).
- 8.Advanced, HER2-negative, PD-L1 CPS ≥5 (or ≥1), first lineNCCN category Category 1 (CPS ≥5), ESMO-MCBS 3 (nivolumab, CPS ≥5)
Nivolumab (CheckMate 649) or pembrolizumab (KEYNOTE-859) or tislelizumab (RATIONALE-305) with FOLFOX or CAPOX; add zolbetuximab if CLDN18.2-positive (sequencing/combination under study).
Zolbetuximab + mFOLFOX6 or CAPOX (SPOTLIGHT/GLOW). PD-L1 CPS ≥5 double-positives: either add-on; combination trials ongoing.
FOLFOX or CAPOX chemotherapy alone; MSI-high tumours get PD-1 blockade regardless of CPS.
Systemic therapy; intraperitoneal paclitaxel, HIPEC, and PIPAC in trials; palliative gastrectomy not recommended (REGATTA).
- 12.Later linesESMO-MCBS 2 (DESTINY-Gastric01 trastuzumab deruxtecan), NCCN Guidelines: Gastric Cancer
T-DXd (HER2+), zanidatamab, CLDN18.2 CAR-T/ADC in trials.
Trastuzumab deruxtecan 6.4 mg/kg (DESTINY-Gastric04, OS 14.7 vs 11.4 months) if HER2 persists on re-biopsy or ctDNA.
Ramucirumab + paclitaxel (RAINBOW, OS 9.6 vs 7.4 months); CLDN18.2-positive: sonesitatug vedotin after CLARITY-Gastric 01 (2026) or satri-cel CAR-T (China).
Trifluridine/tipiracil (TAGS, OS 5.7 vs 3.6 months); irinotecan; clinical trials (FGFR2b, CLDN18.2 bispecifics, T-cell engagers).
Generated from this cancer's standard of care, biomarkers and open problems. Take the group that matches where you are. To tick, add your own and print, open the one-page appointment sheet.
Newly diagnosed
- What is my exact diagnosis, stage, and grade, and which tests established them?Everything else follows from an accurate stage and subtype.
- Which biomarkers have been tested on my tumour (for example HER2, PD-L1 CPS, CLDN18.2, MSI, FGFR2b), and what were the results?These results decide eligibility for targeted therapy, immunotherapy, and trials.
- Which subtype is my cancer, and does that change the recommended treatment?Recognised subtypes for this cancer include Intestinal type, Diffuse / signet-ring type, TCGA: EBV-positive.
- Is germline (inherited) genetic testing recommended for me or my family?Inherited variants can change treatment and matter for relatives.
Localised
- For my situation (localised), which of the standard options do you recommend and why?Guideline options include: Perioperative FLOT ± durvalumab; D2 gastrectomy.
- Am I a candidate for Durvalumab, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Advanced first line
- For my situation (advanced first line), which of the standard options do you recommend and why?Guideline options include: Chemotherapy + PD-1 ± trastuzumab ± zolbetuximab by biomarker.
- Am I a candidate for Nivolumab, Pembrolizumab, Trastuzumab, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Later lines
- For my situation (later lines), which of the standard options do you recommend and why?Guideline options include: T-DXd (HER2+), zanidatamab, CLDN18.2 CAR-T/ADC in trials.
- Am I a candidate for Trastuzumab deruxtecan, Zanidatamab, Satricabtagene autoleucel or related drugs, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Prevention and screening
- For my situation (prevention and screening), which of the standard options do you recommend and why?Guideline options include: H. pylori eradication reduces incidence; endoscopic screening programmes in Japan and Korea (biennial from age 40-50) detect most cancers at a curable stage. No population screening in the West. Prophylactic total gastrectomy for germline CDH1 carriers.
Early (T1a) disease
- For my situation (early (t1a) disease), which of the standard options do you recommend and why?Guideline options include: Endoscopic submucosal dissection for well-differentiated mucosal tumours ≤2 cm without ulceration (expanded criteria in Japan); otherwise gastrectomy.
Resectable stage II-III (Western)
- For my situation (resectable stage ii-iii (western)), which of the standard options do you recommend and why?Guideline options include: Perioperative FLOT + durvalumab (MATTERHORN: OS HR 0.78, pCR 19%) with D2 gastrectomy; FOLFOX/CAPOX perioperatively for patients unfit for docetaxel.
- Am I a candidate for FLOT (5-FU, leucovorin, oxaliplatin, docetaxel), Durvalumab, CAPOX (capecitabine, oxaliplatin), and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of MATTERHORN apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Resectable stage II-III (Asian practice)
- For my situation (resectable stage ii-iii (asian practice)), which of the standard options do you recommend and why?Guideline options include: D2 gastrectomy then adjuvant S-1 (ACTS-GC) or CAPOX (CLASSIC) for 6-12 months; neoadjuvant approaches increasingly adopted.
- Am I a candidate for CAPOX (capecitabine, oxaliplatin), and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Advanced, HER2-positive, first line
- For my situation (advanced, her2-positive, first line), which of the standard options do you recommend and why?Guideline options include: Trastuzumab + fluoropyrimidine/platinum + pembrolizumab (KEYNOTE-811, PD-L1 CPS ≥1); zanidatamab + chemotherapy ± tislelizumab after HERIZON-GEA-01 (PFS 12.4 vs 8.1 months; sBLA 2026).
- Am I a candidate for Trastuzumab, Zanidatamab, Pembrolizumab or related drugs, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of ToGA and HERIZON-GEA-01 apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Advanced, HER2-negative, PD-L1 CPS ≥5 (or ≥1), first line
- For my situation (advanced, her2-negative, pd-l1 cps ≥5 (or ≥1), first line), which of the standard options do you recommend and why?Guideline options include: Nivolumab (CheckMate 649) or pembrolizumab (KEYNOTE-859) or tislelizumab (RATIONALE-305) with FOLFOX or CAPOX; add zolbetuximab if CLDN18.2-positive (sequencing/combination under study).
- Am I a candidate for Nivolumab, Pembrolizumab, Tislelizumab or related drugs, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of CheckMate 649 and KEYNOTE-859 apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Advanced, CLDN18.2-positive (≥75%), HER2-negative, first line
- For my situation (advanced, cldn18.2-positive (≥75%), her2-negative, first line), which of the standard options do you recommend and why?Guideline options include: Zolbetuximab + mFOLFOX6 or CAPOX (SPOTLIGHT/GLOW). PD-L1 CPS ≥5 double-positives: either add-on; combination trials ongoing.
- Am I a candidate for Zolbetuximab, FOLFOX (5-FU, leucovorin, oxaliplatin), CAPOX (capecitabine, oxaliplatin), and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of SPOTLIGHT & GLOW apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Advanced, HER2-negative, PD-L1 CPS <1 and CLDN18.2-negative
- For my situation (advanced, her2-negative, pd-l1 cps <1 and cldn18.2-negative), which of the standard options do you recommend and why?Guideline options include: FOLFOX or CAPOX chemotherapy alone; MSI-high tumours get PD-1 blockade regardless of CPS.
- Am I a candidate for FOLFOX (5-FU, leucovorin, oxaliplatin), CAPOX (capecitabine, oxaliplatin), and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Second line, HER2-positive
- For my situation (second line, her2-positive), which of the standard options do you recommend and why?Guideline options include: Trastuzumab deruxtecan 6.4 mg/kg (DESTINY-Gastric04, OS 14.7 vs 11.4 months) if HER2 persists on re-biopsy or ctDNA.
- Am I a candidate for Trastuzumab deruxtecan, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of DESTINY-Gastric04 apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Second line, HER2-negative
- For my situation (second line, her2-negative), which of the standard options do you recommend and why?Guideline options include: Ramucirumab + paclitaxel (RAINBOW, OS 9.6 vs 7.4 months); CLDN18.2-positive: sonesitatug vedotin after CLARITY-Gastric 01 (2026) or satri-cel CAR-T (China).
- Am I a candidate for Ramucirumab, Paclitaxel / nab-paclitaxel, Sonesitatug vedotin or related drugs, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of RAINBOW and CLARITY-Gastric 01 apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Third line and beyond
- For my situation (third line and beyond), which of the standard options do you recommend and why?Guideline options include: Trifluridine/tipiracil (TAGS, OS 5.7 vs 3.6 months); irinotecan; clinical trials (FGFR2b, CLDN18.2 bispecifics, T-cell engagers).
- Am I a candidate for Trifluridine/tipiracil, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Peritoneal metastases
- For my situation (peritoneal metastases), which of the standard options do you recommend and why?Guideline options include: Systemic therapy; intraperitoneal paclitaxel, HIPEC, and PIPAC in trials; palliative gastrectomy not recommended (REGATTA).
Any stage
- Are there clinical trials I could join, for example of Sonesitatug vedotin, Satricabtagene autoleucel, Disitamab vedotin, Zanidatamab?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?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?Supportive care improves quality of life and helps patients complete treatment.
- I read that “Peritoneal metastasis”. How does that affect my plan?Open problems are where trials and second opinions matter most.
- I read that “Heterogeneous CLDN18.2/HER2 expression”. How does that affect my plan?Open problems are where trials and second opinions matter most.
Trials open now for this cancer in OnCo, largest phase first. Joining a trial is a decision like any other: ask what the comparison arm is, whether a placebo is used, and what happens if you leave. The cancer page searches ClinicalTrials.gov live for more.
- A Clinical Study of Docetaxel for Injection (Albumin-bound) in Patients With Gastric CancerPhase 3 · recruiting · NCT06296706A Multicenter, Randomized, Controlled Phase III Clinical Study of Docetaxel for Injection (Albumin-bound) Versus Taxotere in Gastric Cancer
- A Phase III Clinical Study of Cadonilimab Plus SOX as Perioperative Treatment for Patients With Resectable G/GEJ AdenocarcinomaPhase 3 · recruiting · NCT07023315A Randomized, Double-blind, Phase III Clinical Study Comparing the Efficacy and Safety of Cadonilimab Plus Oxaliplatin and Tegafur-Gimeracil-Oteracil Potassium (SOX) Versus Placebo Plus SOX as Perioperative Treatment for Patients With Resectable Gastric and Gastroesophageal Junction (G/GEJ) Adenocarcinoma
- A Phase Ⅲ Clinical Study of HLX22 in Combination With Trastuzumab and Chemotherapy for the Treatment of Gastroesophageal Junction and Gastric CancerPhase 3 · recruiting · NCT06532006A Randomized, Double-blinded, Multicenter, Phase Ⅲ Clinical Study of HLX22 (Recombinant Humanized Anti-HER2 Monoclonal Antibody Injection) in Combination With Trastuzumab and Chemotherapy (XELOX) Versus Trastuzumab and Chemotherapy (XELOX) With or Without Pembrolizumab for the First Line Treatment of Locally Advanced or Metastatic Gastroesophageal Junction and Gastric Cancer
- A Phase III Randomized Study in CLDN18.2-positive Unresectable Locally Advanced Gastric Cancer PatientsPhase 3 · recruiting · NCT07103668An Open-label, Randomized, Comparative Phase III Study Including Patients With CLDN18.2-positive Unresectable Locally Advanced Gastric Cancer.
- A Phase Ⅲ Study of Rilvegostomig in Combination With Fluoropyrimidine and Trastuzumab Deruxtecan as the First-line Treatment for HER2-positive Gastric CancerPhase 3 · recruiting · NCT06764875A Randomized, Phase Ⅲ Study of Rilvegostomig in Combination With Fluoropyrimidine and Trastuzumab Deruxtecan Versus Trastuzumab, Chemotherapy, and Pembrolizumab for the First Line Treatment of HER2-positive Gastric Cancer (ARTEMIDE-Gastric01)
Much of what helps in the first weeks is free if you know to ask: testing, helplines, rides and lodging, second opinions, trial travel.
- Gastric & gastro-oesophageal junction cancer: the full pageA cancer with three new targets in five years: Claudin 18.2, FGFR2b, and HER2 with new ADCs, plus immunotherapy in first line.
- One-page appointment sheetYour questions, the words you may hear, what to bring, and space for the answers. Print it.
- Guidelines comparedNCCN, ESMO and NICE side by side for this cancer.
- Treatment sequencingWhich treatment tends to follow which, line by line.
- NavigatorStandard of care for your stage, what you have tried, and trials near you.
- Lauren classification (intestinal vs diffuse): Stomach cancers come in two main shapes: intestinal (gland-forming, linked to H.
- ADCC (antibody-dependent cellular cytotoxicity): In ADCC, an antibody flags a cell, and NK cells recognise the flag and kill it.
- Interstitial lung disease (ILD) / pneumonitis: Interstitial lung disease (ILD) is lung inflammation, a serious side effect of some ADCs (especially Enhertu) and immunotherapy.
- FLOT regimen (perioperative chemotherapy for gastric cancer): Four cycles of chemotherapy before and four after surgery for stomach and junction cancer, using fluorouracil, leucovorin, oxaliplatin and docetaxel.
- Oesophagectomy: Surgery that removes most of the food pipe (oesophagus) and rebuilds it by pulling the stomach up into the chest.
- Intraperitoneal (IP) chemotherapy: Delivering chemotherapy directly into the abdominal cavity through a catheter, so the tumour deposits on the lining get a far higher dose than the rest of the body would tolerate.
- Gastrectomy: Removing part (subtotal) or all (total) of the stomach for stomach cancer, with the bowel joined to what remains.
- Gastro-oesophageal junction (GEJ): Where the food pipe meets the stomach.
- Siewert classification (GEJ tumours): A way of classifying cancers at the junction of the oesophagus and stomach by where their centre sits, which decides whether they are treated as oesophageal or gastric.
- Cancer cachexia: Severe loss of weight and muscle in advanced cancer that eating more cannot reverse on its own.
Every term links to the glossary.