When Cancer Comes Back: Lessons From CRS/HIPEC Research

Predictors of Peritoneal Surface Recurrence and Quantitative Association with Time to Relapse After Complete CRS/HIPEC for Colorectal Peritoneal Metastasis. (2026). Cancers. 18. 299. DOI: 10.3390/cancers18020299.

Understanding Recurrence After CRS/HIPEC for Colorectal Cancer Spread to the Abdomen

When colorectal cancer spreads to the lining of the abdomen (called peritoneal metastasis), one treatment option for carefully selected patients is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). This approach aims to remove visible tumors and deliver heated chemotherapy directly into the abdominal cavity to kill microscopic cancer cells. Although CRS/HIPEC can be effective, unfortunately many patients still experience a return of cancer on the peritoneal surface after treatment.

Researchers wanted to understand which factors might help predict whether the cancer comes back on the peritoneal surface after CRS/HIPEC and how quickly this tends to happen.

The colon and rectum

Key Findings

1. Peritoneal Recurrence Is Common

• Nearly half of patients (about 48%) treated with complete CRS/HIPEC for colorectal peritoneal metastasis had cancer return on the peritoneal surface after treatment.

2. Time to Recurrence

• On average, cancer that came back did so after about 41 weeks (roughly 9–10 months) following surgery.

3. Tumor Burden Matters

• The Peritoneal Cancer Index (PCI)—a measure doctors use to describe how much cancer is present in the abdomen—was linked to recurrence:

  • Patients with higher PCI scores were more likely to have the cancer return.

  • Higher PCI scores were also associated with a shorter time until the cancer returned. For example, for every 1-point increase in PCI, recurrence happened about 2.4 weeks earlier on average.

4. Tumor Location Affects Risk

• Where the original tumor started in the colon also mattered:

  • Cancer that began in the right side of the colon or in the sigmoid colon was more likely to come back in the peritoneum after CRS/HIPEC than tumors that began elsewhere.

5. Other Factors Didn’t Predict Recurrence

• Some clinical features — like tumor stage, microscopic tumor type, the specific chemotherapy drug used during HIPEC, and certain genetic changes — were not shown to independently increase the risk of peritoneal surface recurrence in this study.

What This Means for Patients

Understanding which factors are linked to cancer returning on the peritoneal surface may help doctors:

• Better tailor follow-up plans after surgery, including scheduling imaging or other tests more carefully for patients at higher risk.

• Inform discussions about prognosis and expectations after CRS/HIPEC.

• Consider future research to explore how to reduce recurrence risk and improve outcomes for those with higher PCI scores or tumors in certain locations.

Bottom Line

While CRS/HIPEC can offer meaningful disease control for patients with colorectal cancer that has spread to the peritoneum, almost half of patients in this study experienced cancer return on the peritoneal surface. The amount of disease present in the abdomen and the original location of the tumor were linked to both the likelihood and speed of this recurrence. These insights may help guide follow-up care and monitoring strategies after treatment.

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