Treatment options for patients with colorectal cancer that has spread to the peritoneum

This study investigated two treatment options for patients with cancer that has spread to the peritoneum (the lining of the abdominal cavity).

A common location for colorectal cancer to spread is the peritoneum. The best way to treat patients with peritoneal invasion is with cytoreductive surgery plus intraperitoneal chemotherapy (CS/IPC). CS/IPC involves surgically removing affected parts of the peritoneum and then bathing the abdominal cavity in chemotherapy. However, CS/IPC is a risky procedure and in some cases it may not benefit the patient. Predicting which patients would benefit from CS/IPC would help minimize any unnecessary risk to patients.

This study included 180 colorectal cancer patients who underwent treatment for peritoneal invasion. CS/IPC was performed in 77% of the patients, while 23% of patients were not eligible for CS/IPC and received routine chemotherapy instead. The severity of peritoneal cancer was scored from 0 to 39 (scores above 16-20 are normally linked to worse outcome). Patients were followed for an average of 60 months.

At the beginning of the study the CS/IPC group had a lower average peritoneal cancer score (average score 11) than the chemotherapy group (average score 23). At the end of the follow-up period 52% of patients in the CS/IPC group were still alive, compared to only 7% of the chemotherapy group. Rates of survival did not differ significantly between the two groups if patients had a peritoneal cancer score above 17.

Overall, patients with lower peritoneal cancer scores had a better chance of survival compared to patients with higher scores. The risk of death was 6.74 fold higher for patients with a score between 16 and 20 and 11.70 fold higher for patients with a score between 20 and 39, compared to patients with a score between 1 and 4. 

The authors concluded that CS/IPC extends patient survival only if they have a peritoneal cancer score below 17. They suggest that doctors and patients should be aware that if the score is above 17 the benefits of CS/IPS may not outweigh the risks of the treatment.