Gastrointestinal CancerEmerging treatment modalities for gastric cancer with peritoneal metastases: a systematic review.

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TL;DR

A systematic review of 25 prospective studies found that intraperitoneal chemotherapy approaches extend median survival to 13-24 months in gastric cancer patients with peritoneal metastases, compared to 6.5-7.4 months with systemic therapy alone—but evidence remains limited and mostly from Asian centers . Randomized trial data is sparse, limiting definitive treatment recommendations.

What the Study Found

Gastric cancer with peritoneal metastases represents one of oncology's most challenging presentations. These patients typically have advanced disease at diagnosis, historically treated with palliative chemotherapy alone. This systematic review synthesized 25 prospective studies from 9 countries to map the emerging landscape of specialized treatment approaches beyond standard systemic therapy.

The researchers identified four treatment modality categories: traditional systemic chemotherapy, intraperitoneal (IP) chemotherapy delivered directly into the abdominal cavity, hyperthermic intraperitoneal chemotherapy (HIPEC) combined with cytoreductive surgery (CRS), and pressurized intraperitoneal aerosol chemotherapy (PIPAC). The survival differences between approaches were substantial. Median overall survival with systemic chemotherapy alone ranged from 6.5 to 7.4 months—a baseline for comparison. In contrast, IP chemotherapy yielded 13.0 to 23.9 months, HIPEC combined with CRS produced 11.0 to 19.0 months, and PIPAC resulted in 6.8 to 13.0 months. Even elderly patients receiving HIPEC alone achieved 9.9 months median survival.

One particularly notable finding was that patients with high peritoneal tumor burden (Peritoneal Cancer Index ≥20) still achieved median survival of 13 or more months using IP chemotherapy or HIPEC without surgical cytoreduction. This suggests that the therapeutic benefit may not require aggressive surgery in all cases—important since CRS-HIPEC followed by early postoperative IP chemotherapy (EPIC) showed prohibitively high complication rates and significant patient dropout.

However, the review identified a critical limitation: most of these encouraging results came from studies conducted in Asia, primarily in Japan and South Korea. Prospective randomized controlled trials remain sparse. The authors emphasize that current evidence, while suggestive, lacks the randomized trial backbone needed to definitively establish which patients benefit from which approach and how these local treatments integrate with modern systemic therapy, including immunotherapy and targeted agents.

What This Means for You

For patients with peritoneal metastases from gastric cancer: If you're facing this diagnosis, these findings suggest exploring specialized treatment centers experienced with intraperitoneal chemotherapy approaches, particularly if you're in regions where such programs exist. The survival data—more than doubling median survival compared to chemotherapy alone—warrants informed discussion with your oncology team. However, understand that this evidence is not yet standard of care globally, and availability varies significantly by geography.

For treatment planning: The finding that HIPEC/CRS without early postoperative chemotherapy, or IP chemotherapy without surgery, achieved meaningful survival suggests treatment can be individualized. Aggressive cytoreductive surgery is not necessarily required for all patients, which may reduce morbidity. This is clinically relevant since the surgical approach carried substantial toxicity and dropout rates.

For clinical trial participation: The review highlights a genuine evidence gap. Prospective randomized trials comparing these approaches head-to-head, and determining optimal integration with checkpoint inhibitors and targeted therapies, are needed. If available, participation in such trials could advance not only your care but the field's understanding.

Study Details

Sources

Woeste, G., et al. (2024). Gastrointestinal Cancer: Emerging treatment modalities for gastric cancer with peritoneal metastases: a systematic review. *The Oncologist*. PubMed: 40794565

Note: This review synthesizes prospective studies but does not constitute a meta-analysis with pooled effect estimates. Survival outcomes are reported as ranges from included studies and reflect heterogeneous patient populations and treatment protocols. Evidence quality remains moderate due to limited randomized trial data.

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