Immunotherapy around stomach cancer surgery: what studies have shown and what remains open

The starting point

For operable cancer of the stomach, or of the junction between the esophagus and stomach, the standard is FLOT chemotherapy before and after surgery. In the study that established it, typical survival rose from about 35 to 50 months compared with the previous regimen. Even so, only a minority of patients reach surgery with no trace of tumor in the removed tissue, which shows there is room for improvement.

What the immunotherapy studies showed

Two large studies tested adding immunotherapy to treatment around surgery: KEYNOTE-585, with pembrolizumab, and MATTERHORN, with durvalumab.

• In both, more patients reached surgery with no detectable tumor in the removed tissue.
• In KEYNOTE-585, this proportion rose from 2% to about 13%, but the difference in time without the disease coming back was not large enough to be considered conclusive.
• MATTERHORN showed a lower risk of the cancer coming back and was the basis for the US approval of durvalumab with FLOT in November 2025.
• The benefit seems greater in tumors with specific features, such as microsatellite instability (MSI) or expression of the PD-L1 protein.

What this means for you

Immunotherapy around surgery is a new option, but it does not suit everyone equally. Before deciding, it is worth knowing your tumor's profile, such as MSI and PD-L1, and discussing together with your surgeon what each path offers in your case. In MATTERHORN, 68.6% of patients were alive at three years with immunotherapy plus chemotherapy, compared with 61.9% with chemotherapy alone.

What remains open

It is still not clear which patients gain the most, or whether the benefit in time without disease translates into longer life for every group. Future studies need to answer these questions.

For information only. It does not replace an individual medical assessment.