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In a systematic review of 158 patients, neoadjuvant intraperitoneal chemotherapy (IPC) converted positive peritoneal cytology to negative in 78-89% of cases and did not increase serious side effects . However, the evidence base remains small, and these findings require validation in larger randomized trials before clinical adoption can be recommended.
Gastric cancer presents a unique therapeutic challenge: malignant cells frequently spread into the peritoneal cavity (the membrane lining the abdomen) before surgery, often without visible tumors. This transcoelomic spread leads to peritoneal recurrence as a major cause of death even after conventional surgery and chemotherapy. The researchers conducted a systematic review to evaluate whether delivering chemotherapy directly into the peritoneal cavity during the operation, before removing the primary tumor, could improve outcomes in patients at highest risk.
The analysis identified seven studies involving 158 total patients. Among those with cytology-positive disease (meaning cancer cells were detected in peritoneal fluid), the addition of neoadjuvant intraperitoneal chemotherapy converted 78-89% of patients to cytology-negative status, allowing them to proceed to complete surgical removal of their cancer. This conversion rate is clinically meaningful because positive peritoneal cytology at diagnosis normally signals advanced, difficult-to-treat disease. In the cytology-positive group, disease-free survival and overall survival appeared substantially higher than historical controls, though the review did not compare directly against randomized control groups.
The safety profile was reassuring. Neoadjuvant IPC did not appear to significantly increase treatment-related adverse events compared to standard perioperative chemotherapy and surgery alone. Peritoneal-specific recurrence (cancer returning in the abdominal lining) occurred in 63-69% of initially cytology-positive patients but only 0-29% of cytology-negative patients, suggesting the chemotherapy reduced but did not eliminate peritoneal relapse risk in the highest-risk group.
The review also highlighted an important distinction: patients who began treatment with negative peritoneal cytology had substantially better overall survival than those starting with positive cytology, even after IPC treatment. This suggests baseline disease burden matters significantly for long-term outcomes, though the neoadjuvant approach appears to improve prognosis within each risk group.
If you or a family member has been diagnosed with gastric cancer with peritoneal involvement or positive cytology, these findings represent emerging evidence that directly targeting microscopic disease in the peritoneum may improve survival. The approach appears safe in terms of acute toxicity, which is important given that gastric cancer already requires aggressive multimodal treatment.
However, several critical caveats apply:
Discussion with your surgical oncology team about whether neoadjuvant IPC is appropriate for your specific case remains essential, as the evidence supports its investigation but does not yet establish it as routine practice.
| Characteristic | Detail |
|---|---|
| Study type | Systematic review |
| Sample size | 158 patients across 7 included studies |
| Primary outcomes | Disease-free survival (DFS) and overall survival (OS) |
| Secondary outcomes | Adverse events and toxicity |
| Key finding (cytology-positive) | 78-89% conversion to negative cytology; higher DFS and OS |
| Key finding (recurrence) | 63-69% peritoneal recurrence (cytology-positive) vs 0-29% (cytology-negative) |
| Safety signal | No significant increase in treatment-related adverse events |
| Journal | Surgical Oncology |
| Published | 2024 |
| Evidence tier | - systematic review of small studies without RCT comparison |
Xu, Y., et al. "Neoadjuvant intraperitoneal chemotherapy in high-risk and cytology positive gastric cancer: a systematic review." Surgical Oncology, 2024. PubMed: 40446563
About this article: This update describes a systematic review synthesizing evidence from seven published studies. It does not represent a new primary research finding and should not be interpreted as establishing standard clinical practice. Neoadjuvant IPC remains investigational in most healthcare systems. All treatment decisions should be made in consultation with your medical oncology and surgical oncology teams.
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