Patterns of Preoperative Tumor Markers Can Predict Resectability and Prognosis of Peritoneal Metastases: A Clustering Analysis.

backgroundPrediction of open-close and long-term outcome is challenging in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Prognostic scores often include factors not known at baseline. Therefore, we aimed to analyze whether patterns of preoperative tumor markers could aid in prediction of open-close surgery and outcome in patients with pseudomyxoma peritonei (PMP) or colorectal peritoneal metastases (PM). PATIENTS AND

methodsAll patients accepted for CRS and HIPEC for PMP or colorectal PM at Uppsala University Hospital in 2013-2021 were included. The tumor markers CEA, CA19-9, CA125, CA72-4, and CA15-3 were clustered using the k-means algorithm; the average silhouette width determined the optimal numbers of clusters.

resultsClustering of patients with PMP (n = 138) and colorectal PM (n = 213) resulted in two clusters each. PMPCluster-1 (n = 124) had a 5-year overall survival (OS) of 77% (95% CI 69-85%), 11 (9%) open-close surgeries, and a median peritoneal cancer index (PCI) of 17. PMPCluster-2 (n = 14) patients had poorer prognosis (36%, 95% CI 15-85%, p = 0.003), more often open-close (n = 6, 43%, p = 0.002), and higher PCI (median 36, p < 0.001). ColorectalCluster-1 (n = 191) had a 5-year OS of 28% (95% CI 21-37%), median PCI of 11, and 38 (20%) open-close surgeries. ColorectalCluster-2 (n = 22) had poorer prognosis (10%, 95% CI 3-36%, p = 0.02), higher PCI (median 26, p < 0.001), higher completeness of cytoreduction score (p = 0.005), but no difference in open-close surgery (n = 6, 27%, p = 0.411). PMPCluster-2 and ColorectalCluster-2 were characterized by markedly elevated tumor markers. Open-close surgery was unusual in cases of normal CA72-4.

conclusionsElevation of several preoperative tumor markers is associated with poor prognosis and increased risk of open-close. CA72-4 deserves increased attention.