Incidence and outcomes of metachronous peritoneal metastasis in the setting of obstructing colon cancer: a systematic review.

BACKGROUND

Colorectal peritoneal metastases are challenging to diagnose and confer a poorer prognosis than disease recurrence at other sites. Obstruction at presentation in colonic carcinoma is associated with worse survival outcomes. There is little data on its specific influence on the incidence of peritoneal recurrence, including by the varying strategies employed to address the obstruction.

METHODS

A systematic review of the literature was performed to investigate rates of peritoneal recurrence in obstructing colon cancer. The study was pre-registered in the PROSPERO database. The MEDLINE/PubMed, EMBASE, Scopus, Web of Science, and CENTRAL databases were searched for relevant records. Articles published from inception to November 2025 were retrieved and assessed by two independent reviewers.

RESULTS

Of the initial 187 studies retrieved, seven were deemed eligible for inclusion, with a total number of 6578 patients. All were retrospective cohort studies. Reported rates of metachronous peritoneal metastases ranged from 7 to 21%, compared to 2-4% in unselected colorectal cancer populations. Peritoneal recurrence conferred a significantly abbreviated prognosis, with 3-year survival rates of 48-56% compared to 77-85% in those without peritoneal disease.

CONCLUSION

Colonic obstruction at presentation is a risk factor for peritoneal recurrence, which is challenging to diagnose and is associated with poorer survival outcomes than metastatic disease at non-peritoneal locations. Prospective randomised trials investigating strategies to mitigate this risk are warranted.