Could Repeated Intraperitoneal Chemotherapy Improve Treatment for Peritoneal Metastases?
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Kitayama J. Normothermic Intraperitoneal and Systemic Treatment (NIPS) Using Paclitaxel for Peritoneal Metastases from Gastrointestinal Cancer. Cancers. 2026; 18(13):2166. https://doi.org/10.3390/cancers18132166
What was this article about?
When gastrointestinal cancers—such as stomach, pancreatic, or colorectal cancer—spread to the lining of the abdomen (called peritoneal metastases), treatment can be especially challenging. Traditional intravenous (IV) chemotherapy often has difficulty reaching tumors inside the abdominal cavity because of the body's natural peritoneal-plasma barrier, which limits how much chemotherapy reaches these tumors.
This review examines an emerging treatment approach called Normothermic Intraperitoneal and Systemic Treatment (NIPS). NIPS combines standard IV chemotherapy with repeated doses of chemotherapy delivered directly into the abdomen through an implanted catheter or port. The review focuses on paclitaxel, a chemotherapy drug that remains in the abdominal cavity for an extended period and may be particularly effective against peritoneal metastases.
What is NIPS?
Unlike HIPEC, which delivers heated chemotherapy during surgery as a one-time treatment, NIPS uses a small implanted port that allows chemotherapy to be given directly into the abdomen on a regular schedule—often weekly or every other week—without additional surgery or general anesthesia. Patients also continue receiving standard systemic chemotherapy through a vein.
The goal is to attack cancer from both inside the abdomen and throughout the rest of the body, improving drug delivery where it is needed most.
What did the researchers find?
Paclitaxel works well inside the abdominal cavity
Paclitaxel has several properties that make it especially useful for intraperitoneal chemotherapy. After it is placed into the abdominal cavity, it remains there much longer than many other chemotherapy drugs, allowing it to stay in contact with tumors while causing relatively fewer side effects throughout the rest of the body.
Promising results in gastric (stomach) cancer
The strongest evidence comes from patients with gastric cancer and peritoneal metastases.
Across multiple clinical studies, patients treated with NIPS often experienced:
Better control of cancer within the abdomen
Reduction or disappearance of malignant ascites (fluid buildup)
Conversion of positive peritoneal cytology to negative (meaning cancer cells were no longer detected in abdominal fluid)
Improved chances of becoming eligible for surgery after chemotherapy (called conversion surgery)
Longer survival compared with historical outcomes using systemic chemotherapy alone
The review also highlights the DRAGON-01 Phase III trial, which found that patients receiving intraperitoneal paclitaxel plus systemic chemotherapy lived longer than those receiving systemic chemotherapy alone.
Encouraging early results in pancreatic cancer
Patients with pancreatic cancer that has spread to the peritoneum typically have very limited treatment options.
Early phase studies suggest that NIPS may:
Improve disease control
Increase the number of patients able to undergo surgery
Extend survival in selected patients
However, larger randomized clinical trials are still underway to confirm these findings.
Colorectal cancer research is still developing
For colorectal cancer with peritoneal metastases, NIPS has shown encouraging early results, but the evidence is still limited.
At this time, cytoreductive surgery (CRS) with HIPEC and PIPAC remain the better-established regional treatments for carefully selected patients. More research is needed before NIPS becomes a standard option for colorectal cancer.
Why does this matter for patients?
This review highlights an important challenge: standard IV chemotherapy may not reach peritoneal tumors effectively.
Delivering chemotherapy directly into the abdomen allows doctors to expose tumors to much higher drug concentrations while still treating cancer elsewhere in the body with IV chemotherapy.
For some patients, this combined approach may:
Better control cancer inside the abdomen
Reduce symptoms caused by peritoneal metastases
Make surgery possible after an initial response to treatment
Potentially improve survival
What are the limitations?
Although the results are encouraging, NIPS is not yet considered standard treatment for most gastrointestinal cancers.
Most of the strongest evidence comes from studies in Japan and other East Asian countries, particularly in gastric cancer. Additional clinical trials are underway in North America and Europe to determine whether these benefits can be reproduced in broader patient populations. The evidence is also much stronger for gastric cancer than for pancreatic or colorectal cancer.
Bottom line
NIPS is an innovative treatment strategy that combines intravenous chemotherapy with repeated chemotherapy delivered directly into the abdomen. Early research suggests it may improve outcomes for selected patients with gastrointestinal cancers that have spread to the peritoneum—especially gastric cancer. As ongoing clinical trials continue to report results, NIPS could become an important addition to multimodal treatment for carefully selected patients with peritoneal metastases.
