Clinicopathologic Features and Survival Outcomes of Signet Ring Cell Carcinoma of the Appendix: An Analysis of the Surveillance, Epidemiology, and End Results Database

Background and objective Signet ring cell carcinoma of the appendix (SRCCA) is an exceedingly rare tumor, and very limited data are available regarding its characteristics and survival probabilities. Our objective in this study was to utilize the Surveillance, Epidemiology, and End Results (SEER) database to explore the patient and tumor characteristics and to characterize the three- and five-year cancer-specific survival (CSS) probabilities of SRCCA. Methods Patients with SRCCA diagnosed between 2000 and 2015 were analyzed using the SEER database. The three- and five-year CSS probabilities were estimated by the Kaplan-Meier method, and the groups were compared using log-rank comparisons and multivariable Cox hazard regression analysis. Results A total of 527 patients were identified. The median age of the participants at diagnosis was 56 years, with a majority of them being female and white. Histologically, 60% of the tumors were high grade, and 61.3 % of the tumors were found to be metastatic on presentation. Three- and five-year CSS probabilities were 39% and 18.4%, respectively, and median survival was 26 months. Best survival outcomes were noted in males (five-year CSS: 25.4%, p=0.027), unmarried patients (five-year CSS: 19.1%, p=0.042), tumors <2 cm in size (five-year CSS: 50.5%, p<0.001), and low-grade tumors (five-year CSS: 44.8%, p<0.001). Subtotal colectomy yielded better three- and five-year CSS probabilities compared to no surgery and partial colectomy (48.5% and 26.5%, respectively, p<0.001). On the multivariate analysis, it was found that age and stages T4, N1, and M1 were associated with an increased risk of mortality, while surgery, regardless of the extent, was a protective factor. Conclusion SRCCA is a rare tumor with a high prevalence among old-aged white females. This tumor is usually diagnosed in an advanced stage and has a dismal prognosis. Surgical intervention, regardless of the extent, showed better survival probabilities compared to no surgery.