Risk factors of peritoneal metastasis in primary appendiceal tumor

Objective: To investigate the risk factors of peritoneal metastasis in primary appendiceal tumor. Methods: The clinic data of 71 patients with primary appendiceal tumor admitted in the Sixth Affiliated Hospital of Sun Yat-sen University between Dec 2012 and Jan 2019 were enrolled retrospectively. Multivariate logistic regression analysis were carried out to evaluate the risk factors of appendiceal tumor with peritoneal metastasis. Results: Of the 71 patients, 33 were peritoneal metastasis (peritoneal metastasis group) and 38 were non-peritoneal metastasis (no peritoneal metastasis group). Twenty-one patients in the peritoneal metastasis group had increased preoperative cancer embryo antigen (CEA), while 3 cases in the non-peritoneal metastasis group, with statistically significant difference (P<0.001). Sixteen cases in peritoneal metastasis group had increased preoperative carbohydrate antigen 199, while only 2 cases in the non-peritoneal metastasis group, the difference was statistically significant (P<0.001). The pathological type of 30 cases in the peritoneal metastasis group was adenocarcinoma (including mucus adenocarcinoma and colon adenocarcinoma), while 12 cases of adenocarcinoma in the non-peritoneal metastasis group, with statistically significant difference (P<0.001). Twelve cases in the peritoneal metastasis group had lymph node metastasis, while 3 cases in the non-peritoneal metastasis group, the difference is statistically significant (P=0.003). Preoperative CEA elevation and pathological type is adenocarinoma were independent risk factors for peritoneal metastasis of appendiceal cancer (P<0.05). Conclusions: The propensity of peritoneal metastasis in primary appendiceal tumor is high and the outcome is poor. Patients with increased preoperative CEA, adenocarcinoma histopathology are more inclined to have peritoneal metastasis.