When Stomach Cancer Spreads to the Abdomen: A New Treatment Approach Under Study

Maheswari Senthil et al. Phase II trial of systemic therapy plus intraperitoneal (IP) paclitaxel (PTX) in gastric/GEJ cancer peritoneal carcinomatosis (GPC): STOPGAP trial.. J Clin Oncol 44, 359-359(2026). DOI:10.1200/JCO.2026.44.2_suppl.359

What was the study about?

This clinical study looked at whether giving chemotherapy directly into the abdomen (called intraperitoneal chemotherapy) in addition to standard chemotherapy given into a vein (systemic chemotherapy) could help people with gastric (stomach) or gastroesophageal junction (GEJ) cancer when the cancer has spread to the peritoneal lining — a common and difficult-to-treat form of advanced disease.

Who took part in the study?

Adults with stomach or GEJ cancer confirmed by biopsy who had cancer cells in the abdominal cavity but no spread to other organs participated. All patients had first received standard systemic chemotherapy for about 3–4 months. Those whose cancer did not get worse were then treated with both systemic chemotherapy and chemotherapy delivered directly into the peritoneal cavity using a small implanted port.

Why try chemotherapy in the abdomen?

Cancer cells that spread to the peritoneal lining are often hard to reach with standard IV chemotherapy alone, because the bloodstream doesn’t deliver high enough drug levels to the abdominal lining. By giving a portion of the chemotherapy directly into the abdomen (intraperitoneal paclitaxel), the doctors hoped to expose the cancer cells there to higher drug concentrations to better control the disease.

How was the treatment given?

• Chemotherapy was given in two ways:

  • Through an IV (into a vein) in the arm (standard systemic therapy), and

  • Through a port directly into the peritoneal cavity (intraperitoneal paclitaxel).

• Treatments were given on specific days over several weeks in repeating cycles.

Dr. Maheswari Senthil

What did the researchers want to find out?

The main goal was to see how many patients were still alive without their cancer getting worse one year after starting this combined treatment. Other outcomes looked at included overall survival (how long patients lived) and quality of life during treatment.

What were the key takeaways?

• This combined approach — using both systemic chemotherapy and direct abdominal chemotherapy — was feasible and could be delivered safely to most patients who were eligible.

• In some patients whose peritoneal disease responded well, doctors were also able to consider surgery to remove visible cancer, sometimes combined with heated chemotherapy during surgery (HIPEC), which is a more aggressive treatment option.

• While this was a Phase II study (early research), the results suggested that this treatment approach could help control cancer spread in the abdomen better than systemic chemotherapy alone — and may prolong survival — but larger studies are needed to confirm this.

What does this mean for patients?

This trial shows that for some people with advanced stomach or GEJ cancer that has spread to the peritoneal lining, adding intraperitoneal chemotherapy to standard chemotherapy could be a promising strategy. It may help deliver stronger treatment to the cancer cells in the abdomen and offer better disease control than standard treatment alone. Larger future studies (like the ongoing STOPGAP II trial) are underway to find out whether this approach improves long-term survival and should become part of routine care.

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