Tumor-stroma Ratio as a New Prognosticator for Pseudomyxoma Peritonei: a Comprehensive Clinicopathological and Immunohistochemical Study
Abstract Background: As a rare clinical tumor syndrome, pseudomyxoma peritonei (PMP) is usually diagnosed at an advanced stage. In-depth pathological analysis is essential to assessing tumor biological behaviors, assisting treatment decision, and predicting clinical prognosis of PMP. Tumor-stroma ratio (TSR) is a promising prognostic parameter based on tumor and stroma. This study was to explore the relationship between TSR with pathological characteristics and prognosis of PMP.Methods: PMP patients with complete data who underwent last cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy were collected. The TSR of postoperative pathological images was quantitatively analyzed by Image-Pro Plus. Then the relationship between TSR with clinicopathological characteristics, immunohistochemical characteristics and prognosis of PMP was analyzed.Results: Among the 50 PMP patients included, there were 27 males (54.0%) and 23 females (46.0%), with a median age of 55 (31 - 76) years. The patients with histopathological types of disseminated peritoneal adenomucinosis (DPAM) and peritoneal mucinous carcinomatosis (PMCA) were both 25 (50.0%), 4 cases (8.0%) with vascular tumor emboli, 3 cases (6.0%) with nerve invasion, and 5 cases (10.0%) with lymph node metastasis. Immunohistochemical results showed that Ki67 label index was < 25% in 18 cases (36.0%) and ≥ 25% in 32 cases (64.0%). The range of TSR was 2% - 24% (median: 8%). The cutoff value of TSR was 10% based on receiver operating characteristic (ROC) curve. There were 31 cases with TSR < 10% while 19 cases with TSR ≥ 10%. It showed that TSR was closely related to histopathological types (P < 0.001) and Ki67 label index (P < 0.001). Univariate analysis showed that preoperative carcinoembryonic antigen (CEA), preoperative carbohydrate antigen (CA) 19-9, pathological types, vascular tumor emboli and TSR influenced prognosis of PMP patients (P < 0.05). Multivariate analysis showed preoperative CEA, vascular tumor emboli and TSR were independent prognostic factors.Conclusion: TSR could be a new independent prognosticator for PMP.