Oncology

Treatment for Advanced Disease

At a Glance

Treatment for advanced diffuse gastric cancer focuses on systemic therapies tailored to your tumor's unique biomarkers. Targeted drugs like zolbetuximab and immunotherapy can help control the disease, while early palliative care ensures your symptoms are managed for the best quality of life.

When diffuse gastric cancer reaches an advanced or metastatic stage, it means the cancer has spread beyond the stomach to other parts of the body. At this stage, the focus of medical care shifts from “curing” the disease to systemic therapy, which aims to control the cancer, extend life, and improve your daily quality of life ^[1]^[2].

The Challenge of Peritoneal Spread

Diffuse gastric cancer is unique because it has a high tendency to spread to the peritoneum, the thin lining that covers the organs inside your abdomen ^[3]. This is often called peritoneal carcinomatosis.

Why it happens: Because diffuse cancer cells lack the “glue” (E-cadherin) to stay together, they can easily flake off the outer surface of the stomach and “seed” themselves throughout the abdominal cavity ^[4]^[5].
Symptoms: This spread can cause fluid buildup in the abdomen (ascites), leading to bloating, discomfort, and difficulty eating ^[6].
Management: While difficult to treat with surgery alone, doctors may use specialized approaches like HIPEC (heated chemotherapy rinsed through the abdomen during surgery) for very specific cases, or “bidirectional” therapy that combines standard IV chemotherapy with direct abdominal treatments ^[7]^[8].

Biomarkers: Your “Molecular ID Card”

The most important step in treating advanced disease is biomarker testing. This involves checking the tumor’s DNA and proteins to see which “keys” might unlock more effective treatments ^[9].

Biomarker	What it is	Potential Treatment
CLDN18.2	A protein that is often “over-expressed” (too much of it) in diffuse gastric cancer ^[1].	Zolbetuximab: A new targeted drug that hunts down cells with this protein ^[10]^[2].
PD-L1	An “invisibility cloak” some cancer cells use to hide from your immune system ^[11].	Immunotherapy (Nivolumab/Pembrolizumab): These drugs “unmask” the cancer so your immune system can attack it ^[12].
HER2	A growth-promoting protein. Note: HER2 positivity is very rare (under 5%) in the diffuse subtype ^[13].	Trastuzumab: A targeted therapy used if your tumor is HER2-positive ^[14].
MSI-H / dMMR	A sign that the cancer cells have many genetic mutations ^[15].	Immunotherapy: This group often sees the most dramatic results from immune-boosting drugs ^[12]^[15].

Zolbetuximab and the SPOTLIGHT Trial

One of the most significant recent breakthroughs for diffuse gastric cancer involves a drug called zolbetuximab.

The Findings: Two major global studies, the SPOTLIGHT and GLOW trials, found that adding zolbetuximab to standard chemotherapy significantly improved the time patients lived without the cancer growing ^[1]^[10].
Who it’s for: It is specifically for patients whose tumors are CLDN18.2-positive and HER2-negative ^[1]^[16].
What to expect: While effective, it can cause specific side effects like nausea and vomiting, which your team will need to manage with supportive medications ^[17]^[18].

The Role of Immunotherapy

Immunotherapy has become a cornerstone of treatment for many. By measuring your PD-L1 CPS (Combined Positive Score), doctors can predict how likely you are to benefit ^[19]. Generally, a score of 5 or higher suggests the cancer is more likely to respond to drugs like nivolumab when added to your chemotherapy ^[19]^[20]. For the small group of patients with MSI-High status, immunotherapy can sometimes provide very long-lasting control of the disease ^[12]^[15].

Palliative Care: Not “Giving Up”

In advanced disease, palliative care (supportive care) is introduced early. This is not about end-of-life care; rather, it focuses on managing symptoms like pain, nausea, and nutrition ^[21]. For example, if the cancer causes a blockage in the bowel or stomach, doctors can use small tubes called stents to keep things moving and keep you comfortable ^[21]. Combining top-tier cancer treatments with strong supportive care is the best way to maintain your quality of life ^[7].

Common questions in this guide

What does it mean when diffuse gastric cancer spreads to the peritoneum?

Advanced diffuse gastric cancer has a high tendency to spread to the peritoneum, which is the lining of your abdominal organs. This happens because diffuse cancer cells lack the protein needed to stay together, allowing them to flake off and seed throughout the abdomen.

Why do I need biomarker testing for advanced stomach cancer?

Biomarker testing analyzes your tumor's DNA and proteins to identify specific targets for treatment. Discovering markers like CLDN18.2, PD-L1, or MSI-H acts like a molecular ID card, helping your doctor match you with the most effective targeted therapies and immunotherapies.

What is zolbetuximab and am I a candidate for it?

Zolbetuximab is a newer targeted therapy designed to hunt down cancer cells that over-express a specific protein. It is specifically approved for patients whose tumors test positive for the CLDN18.2 protein and negative for the HER2 protein.

What does my PD-L1 score mean for my treatment options?

A PD-L1 Combined Positive Score (CPS) of 5 or higher indicates that your cancer uses a specific protein to hide from your immune system. This score suggests you are more likely to benefit from adding immunotherapy drugs like nivolumab or pembrolizumab to your chemotherapy regimen.

Does starting palliative care mean my medical team is giving up?

No, introducing palliative care early does not mean you are at the end of your life. Palliative care is supportive care focused on aggressively managing symptoms like pain, nausea, and poor nutrition so you can maintain a good quality of life during your active cancer treatments.

Curated prompts to bring to your next appointment.

1.Has my tumor been tested for CLDN18.2, and do I qualify for zolbetuximab based on the SPOTLIGHT trial results?
2.What is my PD-L1 Combined Positive Score (CPS), and how does that influence the decision to add nivolumab or pembrolizumab to my chemo?
3.Is my tumor HER2-positive or HER2-negative?
4.Since diffuse gastric cancer often spreads to the abdominal lining, how are we monitoring for peritoneal metastasis?
5.Are there any clinical trials evaluating PIPAC (Pressurized Intraperitoneal Aerosol Chemotherapy) or HIPEC that I might be a candidate for?
6.What are the most common side effects of zolbetuximab, such as nausea or vomiting, and how will we manage them?

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Guide Contents

Treatment for Advanced Disease

The Challenge of Peritoneal Spread

Biomarkers: Your “Molecular ID Card”

Zolbetuximab and the SPOTLIGHT Trial

The Role of Immunotherapy

Palliative Care: Not “Giving Up”

Common questions in this guide

Questions to Ask Your Doctor

Questions For You

Related questions

Get notified when new evidence is published on diffuse gastric adenocarcinoma.

Guide Contents

The Challenge of Peritoneal Spread

Biomarkers: Your “Molecular ID Card”

Zolbetuximab and the SPOTLIGHT Trial

The Role of Immunotherapy

Palliative Care: Not “Giving Up”

Common questions in this guide

Related questions

References

Get notified when new evidence is published on diffuse gastric adenocarcinoma.